In the future, climate change and rising sea levels are likely to increase the frequency, severity, and impact of coastal storms in New York City (NYC).
What Is the Hazard?
Coastal storms happen when different meteorological conditions converge. Coastal storms are organized systems that have unique characteristics, but each type can turn deadly due to their hazardous consequences — sustained destructive winds, heavy rainfall, storm surge, coastal flooding, and erosion.
New York City experiences hazards from two types of coastal storm systems:
Storm Types
Tropical Cyclones
Tropical cyclones are organized systems of thunderstorms that form over warm tropical ocean waters. These systems rotate counterclockwise in the northern hemisphere around a low-pressure center and are classified into three types:
- A tropical depression is an organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 miles per hour (mph) or fewer.
- A tropical storm is an organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds of 39 to 73 mph.
- A hurricane is an intense tropical weather system of strong thunderstorms with a well-defined low-pressure center (“eye”) and maximum sustained winds of 74 mph or greater.1National Oceanic and Atmospheric Administration, “Tropical Cyclone Climatology,” National Hurricane Center.
Several conditions must be in place for tropical cyclones to form and maintain their intensity. For a tropical cyclone to form, generally, water temperatures at the ocean’s surface must be greater than 80°F at the point of origin. Tropical cyclones that affect New York City originate in the North Atlantic Basin. Conditions that cause tropical cyclones to form are most likely to occur off the western coast of Africa, in the Caribbean Sea, and in the Gulf of Mexico.
Once tropical cyclones form, they often track northward or westward until they reach the mid-latitudes (usually the northern Gulf of Mexico, southeastern United States, or the Northwest Atlantic), where they turn northward or eastward in response to the prevailing winds. However, when certain meteorological conditions coincide, they may track up the East Coast of the United States and head toward New York City.
The Atlantic hurricane season is from June to November. According to the National Hurricane Center (NHC), the Atlantic hurricane season began showing a pattern of heightened activity in 1995 — a trend that continues through today. Scientific studies largely attribute this increase in activity to the Atlantic Multi-decadal Oscillation (AMO), a natural phenomenon characterized by 20–40 year warm and cool cycles in North Atlantic Ocean temperatures.2National Oceanic and Atmospheric Administration, “Atlantic High-Activity Eras: What Does It Mean for Hurricane Season?,” National Oceanic and Atmospheric Administration, October 29, 2019.
The North Atlantic Basin has an average of 14 named tropical storms, seven hurricanes, and three major hurricanes per year.3National Hurricane Center and Central Pacific Hurricane Center, “Tropical Cyclone Climatology,” National Oceanic and Atmospheric Administration. New York City is at highest risk between August and October, when water temperatures are warmest and meteorological conditions in the North Atlantic Basin favor storm formation.
The hurricane risk to New York City peaks in mid-September. Although water temperatures as far north as New York City rarely reach 80°F around this time of year, waters are sufficiently warm to allow strong hurricanes to sustain high energy as they make landfall in the New York region.
When tropical systems make landfall, the primary hazards are heavy rain, high winds, tornadoes, and storm surge. The most dangerous conditions arise in two specific areas of a hurricane — near the center of circulation, or eye wall (the region surrounding the eye), and in the right-front quadrant of the storm, where the hurricane’s high-speed forward motion accelerates the impact of high winds and storm surge.
Heavy rain from tropical systems can occur throughout the duration of a storm. The heaviest rain typically falls on the left side of the storm’s eye. The amount of rainfall depends upon the storm’s speed, size, and the geography of the area it traverses, not on its classification.
The hazards from heavy rain are freshwater flooding when rivers and streams overflow their banks, and inland (flash) flooding in low-lying areas if ground or drainage systems lack the capacity to absorb the unusually high rainfall.
The strongest winds from tropical systems typically occur on the storm’s right side. The primary hazards from strong winds are downed trees and power lines, structural damage to buildings and property, and flying debris.
Tornadoes commonly form either in the right-front quadrant of the storm, in the storm’s eye wall, or in thunderstorms embedded in rain bands far from the storm’s center. Tornadoes produced by tropical cyclones are usually weak and short-lived — but have the potential to pose deadly hazards.
Storm surge is the tropical cyclone hazard responsible for greatest number of deaths based on a study by NHC that looked at fatalities from tropical cyclones from 1963 to 2012.4National Oceanic and Atmospheric Administration, “Storm Surge Overview,” National Hurricane Center. Since the study, the National Weather Service (NWS) and NHC improved educational materials to better communicate the risks of storm surge via real-time storm-surge maps in 2014 and storm-surge watch and warnings emphasizing the life safety risks associated with storm surge in 2017.
In a recent study looking at direct deaths from tropical cyclones from 2012 to 2022, more deaths have been linked to freshwater flooding (57 percent) compared to storm surge (11 percent).5Edward N. Rappaport and B. Wayne Blanchard, “Fatalities in the United States Indirectly Associated with Atlantic Tropical Cyclones,” Bulletin of the American Meteorological Society 97 no. 7, (July 2016): 1139–1148. This may be attributed to improvements in risk communications but also to the prevalence of recent storms that had more rainfall flooding compared to surge impacts. Fatalities caused by surf/rip currents was another notable increase from tropical storms. Rip currents are channeled currents of water flowing away from shore at surf beaches, which can pull people away from offshore and result in drowning.
Direct Fatalities from Weather Related Hazards
| Hazard | Percent of Direct Fatalities 1963 – 2012 | Percent of Direct Fatalities 2013 – 2022 |
|---|---|---|
| Storm Surge | 49% | 11% |
| Freshwater Flooding | 27% | 57% |
| Wind | 8% | 12% |
| Surf/Rip Currents | 6% | 15% |
| Offshore Marine Incidents | 6% | 3% |
| Tornadoes | 3% | 2% |
| Other | 1% | 1% |
Storm surge is the abnormal rise of the water level above the typical astronomical tide level. Storm surge happens as the force of the wind and low pressure of the storm push water toward the shore. During high tides, the surge causes the mean water level to rise even higher, inundating coastal areas. Storm surge is measured by calculating the difference between the normal astronomical tide level and the observed storm water level, or storm tide.
The intensity of the storm surge depends upon several storm characteristics, including the maximum sustained winds, forward speed of the storm, size of the wind field, direction of the storm’s track at landfall, and the geography of the coastline. The most significant storm surge typically occurs near the eye and in the right-front quadrant of the storm.
Combined Effects of Storm Surge, Tide, and Wave Action
Fetch
Wave run-up
Stormtide
Surge
Tide
Datum
An advancing surge combines with a normal tide to create the hurricane storm tide that can inundate a coast. Storm tide is the combined height of the average tide height at the time a storm makes landfall and the surge of water that is pushed toward the land by the storm.
Storm tide values are always referenced to a vertical datum, typically Mean Lower Low Water (MLLW). MLLW is the average height of the lowest tide (lower of the two daily low tides) recorded daily at a tide station.6National Oceanic and Atmospheric Administration, “Tidal Datums,” National Oceanic and Atmospheric Administration.
Inundation caused by storm surge can be measured by the height (or depth) of water above ground level. This is calculated by measuring the height of the total storm tide and subtracting the local land elevation (referenced to a vertical datum). For example, a storm tide height of 20 feet at a land elevation of five feet results in 15 feet of storm-surge inundation.7National Oceanic and Atmospheric Administration, “Storm Surge Overview,” National Hurricane Center.
Coastlines along the open ocean are exposed to two types of tropical cyclone hazards — stillwater flooding from storm surge and tides, and extremely powerful wave action superimposed upon the storm tide. The hazards resulting from this type of extremely forceful wave action include damage to the beach, local buildings, property, and infrastructure.
Nor’easters
A nor’easter is a type of coastal storm that primarily affects the mid-Atlantic and New England states between October and April. Like tropical cyclones, nor’easters are associated with heavy precipitation and a counterclockwise rotation around a center of low pressure. The following chart summarizes the differences between tropical cyclones and nor’easters.8National Weather Service, “What Is a Nor’easter?,” National Oceanic and Atmospheric Administration.
Tropical Cyclone and Nor’easter Characteristics
| Tropical Cyclone | Nor’easter |
|---|---|
| -Forms in tropics or subtropics. -Forms over water. -Derives energy from warm ocean water. -Occurs between June and November -Often associated with bands of severe thunderstorms and possibly tornadoes. -Not associated with wintery precipitation. (snow, sleet, freezing rain) | -Forms outside of the tropics. -Forms and maintains strength over either land or water. -Derives energy from temperature contrasts in the atmosphere. -Occurs between October and April. -Rarely associated with severe thunderstorms and tornadoes. -Often associated with wintry precipitation. (snow, sleet, freezing rain) |
Unlike tropical cyclones, nor’easters form outside of the tropics, typically over the northwestern Atlantic, northern Gulf of Mexico, or central or western United States. Nor’easters can originate and sustain themselves over land and are able to form during the cooler months of the year.
When these storms reach the Northeast or mid-Atlantic coast, the counterclockwise circulation brings winds from a northeasterly direction — hence the name nor’easters. Although nor’easters are typically weaker than hurricanes, they may be larger and have durations lasting multiple tide cycles, creating the risk of more widespread impact. Nor’easters occur more frequently than hurricanes in the New York City area. Due to their frequency, the risk posed by hazards from nor’easters could be considered cumulatively greater than those from hurricanes.
The hazards posed by nor’easters are heavy precipitation, inland flooding, and winds typically strong enough to knock down trees and power lines, causing widespread disruption and structural damage to buildings. Nor’easters may also create coastal flooding from storm surge and large waves.
The hazards of heavy snowfall, sleet, and freezing rain are often associated with nor’easters (see Winter Storms). When a wintertime nor’easter moves up the Atlantic coast and follows a track west of New York City, precipitation often changes from snow or sleet to rain. If a nor’easter maintains a track just off the coast of the city, snow or mixed precipitation likely occurs.
Coastal Storm Attributes/Characteristics
Severity
Tropical Cyclones
The severity of a tropical cyclone depends on multiple factors and is primarily related to potential, expected, or experienced impacts. However, the intensity of tropical storms is formally categorized on the basis of wind speed as measured by the Saffir-Simpson Hurricane Wind Scale. This scale categorizes a hurricane’s intensity on a scale ranging from 1 to 5 based on the storm’s maximum sustained wind speed. Levels of potential property damage are associated with each of the five categories. Hurricanes categorized 3 or higher are considered major hurricanes. This scale does not indicate the amount of surge or rain expected from a hurricane, only wind.9National Hurricane Center and Central Pacific Hurricane Center, “Saffir-Simpson Hurricane Wind Scale,” National Oceanic and Atmospheric Administration.
Category 4 hurricanes in the New York City region are possible, but unlikely. Category 5 hurricanes are not anticipated to occur in the New York City area, because they are not meteorologically sustainable over the Atlantic Ocean north of Virginia.
Although the Saffir-Simpson Hurricane Wind scale is a practical way of measuring hurricane strength, other factors contribute to a hurricane’s impact on a given location — including the storm’s size (proportional to the radius of maximum winds) and speed of its forward motion. A larger, slower-moving storm, for example, may cause greater damage than a smaller, faster-moving storm with high winds because a single location might be battered by winds from a slower-moving hurricane for a longer period of time.
The wind’s fetch — the distance that the wind blows across the water’s surface — and its duration also affect a tropical cyclone’s severity. Wind fetch is determined by the radius of maximum winds and forward speed of the tropical storm. The severity of waves and height of the storm surge is directly affected by how far and how long a specific storm’s winds blow across the water.
The bearing of a storm — the direction that it is moving — when it reaches New York City also contributes to the severity of its impact. Its bearing determines the wind direction, which affects the height and severity of the storm surge.
The local geography of the coastline amplifies storm surge in the New York City region. The New York Bight — the nearly 90-degree angle formed by the shorelines for Long Island and New Jersey — can funnel a storm surge directly into New York Harbor.10Brian A. Colle and David R. Novak, “The New York Bight Jet: Climatology and Dynamical Evolution,” Monthly Weather Review 138 no. 6 (June 2010): 2385–2404. Storms with a westward bearing often generate higher storm-surge risk.
For New York City, the worst-case hurricane track is a storm making landfall just to the south along the coast of New Jersey. In this scenario, the city is in the right-front quadrant of the storm as the storm funnels the surge directly into Raritan Bay and New York Harbor.
This scenario is precisely what happened in 2012 during Hurricane Sandy and why the storm had such a disastrous impact on New York City. Hurricane Irene made landfall over Brooklyn in 2011 — but was a very different tropical storm than Sandy. At landfall, Hurricane Irene’s bearing was north-northeast, which did not create the direct surge impacts that Hurricane Sandy inflicted on New York City just over one year later.11NYC Special Initiative for Rebuilding and Resiliency, “Chapter 1: Sandy and Its Impacts,” City of New York, June 11, 2013.
Nor’easters
Nor’easters do not have a universally recognized classification system, but their strength and severity are influenced by factors similar to those discussed regarding the severity of tropical storms.
When a nor’easter produces a heavy snowfall, the Northeast Snowfall Impact Scale (NESIS) is used to measure the intensity of wintry precipitation. The NESIS characterizes and ranks high-impact Northeast snowstorms — those with large areas of snowfall accumulations of 10 inches and greater — on a scale of 1 to 5.
The National Climatic Data Center developed this scale to indicate the degree to which Northeast snowstorms might affect the transportation systems and economy of the region and thereby impact the rest of the country. The NESIS index incorporates population data and meteorological measurements to gauge a nor’easter storm’s overall impact.
Probability
Tropical Cyclones
NHC forecasts storm tide heights for tropical storms and hurricanes on a probabilistic basis (a range of likely storm tide levels) and updates its forecasts regularly as specific storms approach landfall.
The NHC calculates return periods for hurricanes for various locations along the East Coast of the United States. These return period calculations represent the average amount of time between the passage of two hurricane eyes within a 50-nautical-mile (57.54-mile) radius of a given location.12National Hurricane Center and Central Pacific Hurricane Center, “Tropical Cyclone Climatology,” National Oceanic and Atmospheric Administration.
According to these NHC probability models, New York City should expect to experience a lower-category hurricane on average once every 19 years and a major hurricane (Category 3 or greater) on average once every 74 years.
Nor’easters
The National Oceanic and Atmospheric Administration (NOAA) provides timely storm tide forecasts for nontropical storms (including nor’easters) on a deterministic basis (a single value for each tide gauge location). New York City typically experiences several nor’easters of different intensity every year. Most of these nor’easters are relatively weak but retain the potential to produce significant rainfall or snowfall hazards that can cause minor-to-moderate damage across the area. The probability of severe nor’easters affecting New York City is low, but they do strike occasionally.
Some academic institutions, including Stevens Institute of Technology and SUNY Stony Brook, provide forecasting services similar to NOAA. Although conducted purely for research purposes, their forecasts are often valuable supplements to official forecasts.
Location
Tropical Cyclones
The vulnerability of different neighborhoods and areas of New York City to hazards associated with tropical storms varies significantly. To predict storm surge and to guide the City’s planning for coastal storms, New York City Emergency Management (NYCEM) utilizes outputs from an NHC computer model called SLOSH (Sea, Lake, and Overland Surges from Hurricanes).
The SLOSH model calculates surge heights for storms that move in different directions and vary in strength from Category 1 to Category 4. Calculations are based on the different wind speeds associated with Category 1–4 storms, the radius of maximum winds, and the storm’s forward speeds, storm bearing, and tides. The SLOSH model calculates surge levels for specific locations assuming that each location is hit by the most intense part of a storm. The SLOSH model uses all of these factors to generate a worst-case scenario for storm surge at specific locations in New York City — it does not relate to probability of occurrence.
The NYC Hurricane Evacuation Zones map shows areas of the city likely to experience inundation from different categories of storms, based on the SLOSH model calculations. The extent of inundation and storm-surge depths indicated on the map reflect the worst-case scenario for Category 1–4 hurricanes in different parts of New York City.
NYC Hurricane Evacuation Zones
Source: NYCEM GIS
The red areas on the map represent the areas of the city that could be inundated by storm surge in a worst-case scenario from a Category 1 hurricane.
NYCEM utilizes SLOSH data to develop evacuation zones for the New York City Coastal Storm Plan (CSP). Evacuation zones are based on a SLOSH output called Maximum Envelope of Water (MEOW). MEOWs show the maximum surge inundation from a set of hypothetical storms of fixed size at specific landfall locations with varied intensity, forward speed, storm direction, and tide anomaly.
The CSP evacuation zones employ a range of possible scenarios from the MEOWs, in contrast to the SLOSH maps that only display one worst-case scenario storm surge — the MOM (Maximum of MEOWs) for each category.
Evacuation zones presume a universal worst-case scenario, as if a storm were to make landfall in all parts of the city at once, creating the maximum amount of potential surge inundation in each location. Evacuation orders are issued for an entire zone due to the inherent uncertainty in the forecast, even though a storm will not create worst-case effects in every part of the zone.
The City updated its evacuation zones in 2021. Unlike the set of evacuation zones which were in place when Hurricane Sandy struck in 2012, the storm’s bearing is now a more significant input for the calculation of the new zones.
Nor’easters
SLOSH data is not used for nor’easters. However, the NWS provides water level forecast ranges referenced to several different data points that reference water levels by a phase of the tide. The two most common tidal data references that are used for tidal gauges around the New York City metro region ahead of an impending coastal flood event include Mean Higher High Water (MHHW) and Mean Lower Low Water (MLLW). NOAA’s Office for Coastal Management Sea-Level Rise Viewer and NWS New York Impact Catalogs are used to determine the potential impacts from that storm.
Historic Occurrences
To see records of coastal storms affecting New York City since 1785, use the Hazard History and Consequence Database, an interactive tool developed for this website.
Since the 2019 NYC Hazard Mitigation Plan, there have been several notable tropical or tropical-connected systems that have affected NYC. Each produced different impacts:
Tropical Storm Isaias impacted the Tri-state area on August 4, 2020. Winds were the most damaging element of the storm, with peak gusts of 70 mph recorded at JFK airport. The southeast wind component was also a major contributing factor to the 28,000 tree emergencies in Brooklyn and Queens, as trees in the city have been “trained” to withstand west-northwest winds, which is a much more common wind direction. A Flash Flood Watch was issued by NWS two days before the storm. However, Isaias eventually took a slightly more westward track across far eastern Pennsylvania, sparing the city the worst of the heavy rains, with Central Park recording just under 0.5 inch of total rainfall. Coastal flooding was also a potential threat with aboveground inundation of one to three feet predicted the day before the storm. Thankfully, Isaias’ peak surge did not coincide with the astronomical high tide, resulting in only isolated minor flooding along NYC’s shorelines.13Isaias Task Force, Tropical Storm Isaias 30-Day Report, Long Island Power Authority, September 23, 2020.
On the afternoon of July 8, 2021, one day before Tropical Storm Elsa passed to the south and east of NYC, a predecessor rainfall occurred. According to radar estimates, three to four inches of rain fell in only a few hours across northern Manhattan and the Bronx. A NYS Mesonet site in the Bronx recorded just over three inches of rain in one hour. This flash flood event resulted in significant delays and damage on the A Train in northern Manhattan and multiple water rescues along the Major Deegan Expressway. Another round of heavy rainfall was predicted for the following day as the storm made its closest approach to the city. Fortunately, Elsa did not produce any rainfall in NYC on July 9.14John P. Cangialosi, Sandy Delgado, and Robbie Berg, National Hurricane Center Tropical Cyclone Report: Hurricane Elsa, National Oceanic and Atmospheric Administration, February 10, 2022.
Hurricane Henri produced two rounds of flash flooding on August 21 and 22, 2021. The first was another predecessor rain event in connection to Hurricane Henri on the evening of August 21, 2021. That night, large portions of Brooklyn, the Bronx, Manhattan, and Queens saw two to five inches of heavy rain in only a few hours. Central Park observed nearly 4.5 inches of rain, most of which fell between 9 p.m. and midnight. Central Park also broke its hourly rainfall record in the modern sensing era, observing 1.94 inches of rain between 10 p.m. and 11 p.m. The next day, as Henri made its closest approach to the city before making landfall around noon in Rhode Island as a weakening tropical storm, additional heavy rainfall of two to four inches fell across Brooklyn and Queens. In comparison to Elsa, rainfall rates were slightly lower, at one to two inches per hour; however, the coverage of heavy rain was much greater, with nearly all of Brooklyn and Manhattan, and portions of Queens and the Bronx, seeing six to eight inches of storm total rainfall.15National Weather Service, “August 22: Heavy Rain and Flooding Associated with Henri,” National Oceanic and Atmospheric Administration.
Only 10 days later, on September 1, 2021, Post-Tropical Cyclone (PTC) Ida impacted the Tri-state area. Originally making landfall in Louisiana as a hurricane on the morning of August 29, the storm quickly weakened into a tropical storm and eventually a tropical depression over the Tennessee River Valley as it progressed northeastward toward New York. As a PTC, it eventually interacted with a stationary boundary over Virginia to produce a truly unprecedented and historic flash flood event in NYC. While rain was observed for nearly 12 hours over the course of the day, the vast majority fell in only three to five hours that evening. Only southeast Queens was spared the worst of the heavy rains as nearly every square inch of NYC saw between four and nine inches of total rainfall. Central Park again broke its hourly rainfall rate in the modern sensing era, recording 3.15 inches of rain between 9 p.m. and 10 p.m. Elsewhere, peak rainfall rates of 3.5 to 4 inches per hour were recorded by radar and other ground sensors. Ida also presented a severe thunderstorm risk, with a tornado warning issued for Harlem that night. Fortunately, no touchdown was observed. Gusty winds of 35 to 40 mph were also recorded, although this did not result in significant impact.16National Weather Service, “September 1: Remnants of Ida,” National Oceanic and Atmospheric Administration.
The map titled NYC Significant Coastal Storms (1856-2021) shows the tracks of coastal storms to come within 100 miles of New York City between 1856 and 2021.
NYC Significant Coastal Storms (1856-2021)
Source: NYCEM GIS
What Is the Risk?
Many factors make New York City particularly vulnerable to major coastal storms and their secondary impacts. Based on the SLOSH modeling, storm-surge inundation areas of the city have nearly 2.8 million city residents, a significant amount of extremely valuable real estate, and a vast network of critical interconnected infrastructure.
Because New York City serves as a global financial center and the hub of a large, complex regional economy, damage from coastal storms has repercussions beyond the city’s borders. If a major coastal storm were to impact northern New Jersey or Long Island, New York City’s close proximity makes it likely that the secondary consequences of those storms would also have an impact here.
The following sections discuss the consequences of major coastal storms upon New York City. Additional, related consequences are detailed in the High Winds and Flooding profiles.
Social Environment
Coastal storms can have a significant impact on the population of New York City. Based on population figures from the 2020 Census, nearly 2.8 million New York City residents live within a storm-surge inundation area, putting them at increased risk. In the event as described in the What Is the Hazard section (Expand Location & Expand Tropic Storms), worst-case inundation scenarios — modeled using the SLOSH output called MEOW — were used to create evacuation zones in the CSP. The evacuation zones were developed based upon a range of possible scenarios from the MEOWs.
Estimated Population in Storm-Surge Inundation Areas from SLOSH Model (By Storm Category)
| Storm Category | Estimated Population (inclusive of each other) |
|---|---|
| Category 1 | 735,000 |
| Category 2 | 1,325,000 |
| Category 3 | 1,904,000 |
| Category 4 | 2,813,000 |
Based on population figures from the 2020 Census, about 3.4 million New York City residents live in a Storm-Surge Evacuation Zone and could be asked to evacuate during a coastal storm event.
Estimated Population in Storm-Surge Inundation Areas from SLOSH Model (By Evacuation Zone)
| Evacuation Zone | Estimated Population (inclusive of each other) |
|---|---|
| Zone 1 | 460,000 |
| Zone 2 | 940,000 |
| Zone 3 | 1,310,000 |
| Zone 4 | 1,910,000 |
| Zone 5 | 2,580,000 |
| Zone 6 | 3,430,000 |
As mentioned earlier in the profile, storm surge and rainfall flooding account for the highest risk to direct life safety during a coastal storm. A recent study by the NHC identified other factors that resulted in indirect deaths from coastal storm events. Traffic accidents (16 percent) and cleanup from coastal storms (15 percent) account for the highest risks to life safety. This is followed by carbon monoxide poisoning (12 percent), lack of medical care (11 percent), and power problem/electrocution (11 percent). Fifty-seven percent of victims of indirect deaths were over the age of 60.17Michael Brennan, Daniel Brown, and Leah Pope, “Recent Trends in Tropical Cyclone Fatalities in the United States,” The Front Page (blog) of The American Meteorological Society, August 8, 2023.
New York City residents, particularly at-risk populations such as the elderly, people who are physically or mentally disabled, people with underlying health conditions, or others who require access or functional assistance, could be exposed to significant safety and health risks during a storm and after it has passed. Health risks could result from direct exposure to the impact of the storm — people may drown in rising waters, get struck by flying debris and falling trees, or be electrocuted by fallen power lines.
People may also be forced to shelter in inadequate housing that lacks heat or hot water. They may be exposed to contaminated floodwaters, spoiled food, or mold. Further, they may experience the complete disruption of basic services. Rain, wind, and runoff may also contribute to high levels of turbidity (suspended pollutants) in local reservoirs, which interferes with the disinfection of drinking water.18Char Adams, “Women in New York Prisons Complain of Contaminated Water after Hurricane Ida,” NBC News, September 14, 2021.
Risk factors that increase people’s vulnerability to coastal storms include lack of mobility, language barriers, and lack of access to medical resources. People aged 65 and over are highly likely to be physically disabled or have preexisting medical conditions that make evacuation more difficult — particularly in elevator buildings during utility outages. People who rely on life-sustaining equipment in their homes are at increased risk if coastal storms create power outages — and otherwise.
New York City has a large population of immigrants, including many people who do not speak fluent English. Language barriers may make it more difficult for these segments of the population to receive and understand storm and emergency warnings, and to access post-storm recovery resources. These barriers could inhibit their ability to translate these warnings into lifesaving action and access recovery aid (refer to New York City’s Vulnerability Assessment). After PTC Ida, a NYCEM analysis found that community districts with the highest rates of damage speak languages other than English at home. Spanish is spoken at home at much greater rates in the most damaged neighborhoods. This is followed by rates of “Other European” and “Other” language speakers. “Other European” languages include Indo-European languages like Urdu, Hindi, Punjabi, Bengali, and Nepali. “Other” consists of a range of unrelated languages, including Somali, Jamaican Creole, and several Western African languages. In contrast, in communities with the lowest damage rates, English is the majority language spoken at home.
People with disabilities and other access and functional needs are also at increased risk because of their disproportional reliance on health care facilities. Hospitals, nursing homes, adult care facilities, and pharmacies may shut down or operate at reduced capacity during coastal storms. Patients and residents of these types of facilities are at risk during coastal storms due to power loss, especially people who rely on life-support equipment, such as ventilators that operate with electricity. Approximately one-third of New York City’s hospitals and nursing homes are located in storm-surge inundation areas. If backup generators and other types of essential equipment are located on lower floors, equipment might cease to operate if lower floors flood.
Coastal storms can strain the health care system as a whole. As facilities in inundation zones are evacuated or otherwise incapacitated, remaining operational facilities in the health care system become stressed. A storm’s impact may result in an increased number of patients seeking essential medical treatment at a limited number of increasingly overcrowded medical facilities with limited space. As a result, some patients may be unable to receive treatment. During or after a coastal storm, medical facilities and nursing homes find it particularly challenging to evacuate patients with critical ailments or injuries.
People who do not evacuate during a coastal storm and choose to shelter in place are also at increased risk for several reasons. Those sheltering in place may experience delayed responses from medical personnel due to lack of transportation, limited access to certain areas, nonfunctioning medical facilities, or high volumes of emergency calls. Power outages may disable systems that use electric pumps to distribute water to upper floors of high-rise buildings, stranding people without potable water or water for washing and flushing. Residents living in high-rise buildings also risk being stranded if they live on higher floors and lose the power that runs their elevators.
If storms knock out or damage essential utilities or building systems and if extremely hot or cold weather follows, people are exposed to greater risk by the lack of air-conditioning or heat. If residents are stranded in flooded or damaged homes after the storm passes, they risk being exposed to secondary health hazards, such as contaminated drinking water or growth of toxic mold. If people are without power for an extended period after a storm, the health risks associated with food spoilage increase.
Following a major storm or other disaster, people who are directly, significantly affected may also experience (or experience exacerbated) mental health problems, such as post-traumatic stress disorder, anxiety, and mood disorders. These mental health impacts are most common in the months immediately following a storm, but can potentially last much longer depending upon the severity of the storm, the nature of their exposure, chronic stress factors related to the storm (such as prolonged displacement or power disruption), preexisting mental health issues, and access to adequate care and assistance.
Built Environment
Buildings and infrastructure in New York City are vulnerable to significant damage during coastal storms. This section discusses the risk to New York City’s built environment, including its building stock, the potential risk to buildings due to coastal storms, and infrastructure.
Building Stock
The vulnerability of buildings to storm surge and storm damage in New York City varies according to the height of the building, its type of construction, the building’s age, the residential subsurface space, and its location.
Low-rise buildings situated in inundation areas in New York City are more vulnerable to coastal storm damage and destruction than mid-rise and high-rise buildings for several reasons. Because low-rise buildings have more floor area closer to the ground than other types, a larger proportion of these buildings will be damaged by the storm surge. Low-rise buildings are often built from lightweight materials, so they are more susceptible to structural damage than high-rise buildings with steel, masonry, or concrete frames.
As buildings rise higher, their facades are more vulnerable to damage from extreme winds. Wind speed could be equivalent to speeds of one storm category stronger for every 30 stories of a building’s height. For older buildings not designed to modern standards, the higher wind speed associated with the higher floors of tall buildings could lead to broken windows and falling debris that puts people below and inside the building at risk. Despite containing proportionally less combustible material than other building types, high-rise buildings are vulnerable because of a different set of fire hazards, such as the difficulties associated with a complex vertical response and evacuation operations due to the building’s height.
The susceptibility of the built environment to flood damage depends on the specific characteristics of the storm and the location of buildings. For example, buildings situated along the open coast are not only subject to higher wind speeds but also to the destructive force of wave action. This may cause more serious damage than would be suffered by buildings away from the coast that are subject only to stillwater flooding.
During Hurricane Sandy, which flooded 9 percent of the city’s building stock, much of the sustained building damage was caused by surge force and depth of inundation. A significant proportion of the building damage during Hurricane Sandy was not structural; rather, it was largely related to ground-floor and basement flooding where building and electrical systems were located. Building age is an important indicator of structural vulnerability. Older buildings are more vulnerable to coastal storm damage than newer buildings because they were built before the increased stringency of more recent building and zoning standards. During Hurricane Sandy, for example, structures built before New York City’s 1961 Zoning Resolution — and before implementation of the 1983 federal standards associated with Flood Insurance Rate Maps (FIRMs) from the Federal Emergency Management Agency (FEMA) — suffered more severe damage than newer buildings. Many New York City Housing Authority (NYCHA) facilities that were built before implementation of the 1983 standards sustained significant damage from Hurricane Sandy.
Buildings with basements or subsurface spaces are also at risk of flooding during tropical cyclones that produce heavy rainfall. That vulnerability is amplified when the area is used as residential space. Tragically, 11 people lost their lives from drowning in their basement apartments during PTC Ida. An analysis looking at damage impacts from this storm indicates that more than half (55 percent) of the impacted buildings and homes had some form of observable subsurface space. As the map below indicates, most of these buildings are spread out across Brooklyn, Queens, and parts of the Bronx. While basement apartments are not permitted in the FEMA floodplain, most of the impacted buildings from PTC Ida were inland neighborhoods across New York City. Approximately 93 percent of the impacted buildings were located outside the FEMA 100-year floodplain.19Thompson, Andrea, “New York City’s Floods and Torrential Rainfall Explained,” Scientific American, September 29, 2023.
Post-Tropical Cyclone Ida Damaged Buildings with Subsurface Space
The damage to New York City from Coastal Storms is also significant. Since 2011, New York City has had four storms that resulted in such extreme damage that FEMA responded by awarding Public Assistance grants and/or Individual Assistance.
Financial Impacts of Coastal Storms (2011–2022)
| Date | Storm Name | Individual Assistance (IA) | Public Assistance (PA) | Total |
|---|---|---|---|---|
| 08/27/2011 | Irene | $20,000,000 | $31,000,000 | $51,000,000 |
| 10/29/2012 | Sandy | $773,000,000 | $7,600,000,000 | $8,373,000,000 |
| 08/03/2020 | Isaias | N/A | $11,000,000 | $11,000,000 |
| 09/01/2021 | Ida | $135,000,000 | N/A | $135,000,000 |
Potential Building Losses due to Winds and Storm Surge from Coastal Storms
To estimate potential building losses and economic impact from various potential Coastal Storm scenarios, NYCEM leveraged a contractor (IEM) to run several loss estimation models using Hazards US Multi-Hazard (HAZUS-MH) software. HAZUS uses demographics, facilities, infrastructure, and buildings, along with risk data specific to each hazard, and damage models to estimate losses to a given area. Scenarios for each hazard can be deterministic (defined by a specific event) or probabilistic (defined by a return period). The probability is expressed by a percent chance that a hurricane of a specific magnitude will occur in any given year. For example, a hurricane with a 50-year return period has a 2 percent chance of occurring in any one year. For the Coastal Storms hazard, IEM ran a probabilistic hurricane scenario for return periods of 10, 20, 50, 100, 200, 500, and 1,000 years.
Hurricane Return Period and Chance of Occurrence
| Return Period (Years) | Chance of Occurrence in Any Given Year (%) |
|---|---|
| 20 | 5 |
| 50 | 2 |
| 100 | 1 |
| 200 | 0.5 |
| 500 | 0.2 |
| 1,000 | 0.1 |
The Coastal Storm hazard combines a hurricane and flood hazard scenario in HAZUS to analyze wind and storm-surge flooding. Because the software cannot run both wind and flooding impacts as probabilistic runs, IEM ran an intermediate probabilistic run to generate storm track and wind speed data for use in the custom user-defined storms for the six return periods and then ran a storm-surge analysis for each return period.
A probabilistic hurricane run in HAZUS considers the impact of thousands of potential coastal storms that reflect the full spectrum of Atlantic hurricanes. This approach is validated by comparing site-specific statistics of key hurricane parameters of the simulated hurricane tracks with statistics derived from historical data. A user-defined storm track differs from the probabilistic scenario in that it considers one storm track with specific hurricane parameters to replicate a “real-life” simulation of an individual storm.
The HAZUS-MH hurricane module has five classifications of damage — None, Minor, Moderate, Severe, and Destruction. Thus, wind-related structural damage is simplified into one of five basic categories. The table titled HAZUS-MH Estimates: New York City Buildings Subject to Wind and Storm-Surge Damage from Coastal Storms outlines how these damage states apply to residential structures.20FEMA, HAZUS Hurricane Model Technical Manual: HAZUS 5.1, Federal Emergency Management Agency, July 2022.
Estimates of the number of New York City buildings that would be subject to damage from coastal storms over these time intervals are shown in the table. The number of damaged buildings increases as the return interval goes up, but probability goes down. For example, over a 50-year interval or 2 percent probability of occurrence, 180 buildings in New York City could suffer severe damage due to wind and storm surge from coastal storms, whereas a 1,000-year interval or 0.1 percent probability of occurrence results in 14,580 buildings with severe damage.
HAZUS-MH Estimates: New York City Buildings Subject to Wind and Storm-Surge Damage from Coastal Storms
| Scenario | Minor | Moderate | Severe | Destruction | Total | % of Building Stock Damaged |
| 20-year | 2,420 | 150 | 5 | 0 | 2,575 | 0.24% |
| 50-year | 27,730 | 4,570 | 180 | 1 | 32,481 | 3.00% |
| 100-year | 59,990 | 14,540 | 660 | 170 | 75,360 | 6.95% |
| 200-year | 130,640 | 61,000 | 1,340 | 240 | 193,220 | 17.82% |
| 500-year | 206,080 | 72,360 | 4,990 | 1,460 | 284,890 | 26.28% |
| 1000-year | 327,940 | 144,290 | 14,580 | 4,710 | 491,520 | 45.34% |
HAZUS-MH was also used to calculate the dollar value of losses from wind damage and storm-surge damage from coastal storms affecting New York City over the same time intervals. The table titled HAZUS-MH Estimates: Total Loss Values for Coastal Storm Combined Wind and Storm-Surge Damage by Return Period shows the results of these estimates, which includes the value of damage to buildings, the contents of buildings, inventory, and associated loss of income. Like the number of damaged buildings, economic losses also increase as the return period intervals increase and probability decreases. For example, over a 20-year interval or a 10 percent chance of occurrence, cumulative economic losses from coastal storm wind and storm-surge damage in New York City are estimated at approximately $389 million. For a 1,000-year event or a 0.1 chance of occurrence, damages from coastal storm winds and storm-surge damage are estimated at over $92 billion in cumulative economic losses. Note that these values are approximate, calculated to the nearest thousand dollars.
HAZUS-MH Estimates: Total Loss Values for Coastal Storm Combined Wind and Storm-Surge Damage by Return Period
| Scenario | Building Loss | Contents Loss | Inventory Loss | Total |
| 20-year | $357,930,000 | $31,330,000 | $290,000 | $389,560,000 |
| 50-year | $5,738,860,000 | $750,930,000 | $6,450,000 | $6,496,240,000 |
| 100-year | $15,358,440,000 | $6,345,680,000 | $126,630,000 | $21,830,750,000 |
| 200-year | $1,009,320,000 | $1,371,060,000 | $80,670,000 | $2,461,050,000 |
| 500-year | $53,600,450,000 | $19,570,990,000 | $480,600,000 | $73,652,030,000 |
| 1,000-year | $74,826,010,000 | $17,323,390,000 | $358,530,000 | $92,507,920,000 |
The next set of tables and interactive map below show damages incurred from probabilistic return periods by borough for the same return intervals (20-year, 50-year, 100-year, 200-year, 500-year, and 1,000-year). As mentioned above, one of the limitations of the HAZUS software is that probabilistic runs cannot be run for both wind damage and storm-surge impacts; therefore, each return period has a different hurricane storm track used to model storm-surge impacts before combining the estimates with the wind damage loss estimates. This explains why damages across the city vary geographically by return period. For example, the 100-year return period storm impacted Manhattan the hardest, with cumulative damaged estimated at $10 billion, compared to Brooklyn at only $6.4 billion. Whereas, the 1,000-year return period impacted Brooklyn the hardest at $30 billion compared to Manhattan at $20 billion.
HAZUS-MH Estimates: NYC Economic Losses from a Coastal Storm Wind and Storm Surge by County — 20-Year
| Borough | Building Loss | Contents Loss | Inventory Loss | Total |
| Bronx | $59,140,000 | $4,160,000 | $1,000 | $63,301,000 |
| Kings | $109,540,000 | $8,500,000 | $180,000 | $118,220,000 |
| New York | $103,640,000 | $10,290,000 | $100,000 | $114,030,000 |
| Queens | $62,190,000 | $7,930,000 | $11,000 | $70,131,000 |
| Richmond | $23,430,000 | $450,000 | $1,000 | $23,881,000 |
| Total | $357,940,000 | $31,330,000 | $293,000 | $389,563,000 |
HAZUS-MH Estimates: NYC Economic Losses from a Coastal Storm Wind and Storm Surge by County — 50-Year
| Borough | Building Loss | Contents Loss | Inventory Loss | Total |
| Bronx | $998,210,000 | $115,000,000 | $860,000 | $1,114,060,000 |
| Kings | $1,770,060,000 | $214,890,000 | $1,990,000 | $1,986,930,000 |
| New York | $1,081,160,000 | $218,810,000 | $610,000 | $1,300,580,000 |
| Queens | $1,733,000,000 | $192,010,000 | $1,980,000 | $1,926,990,000 |
| Richmond | $90,430,000 | $4,240,000 | $4,000 | $94,674,000 |
| Total | $5,672,860,000 | $744,950,000 | $5,444,000 | $6,423,234,000 |
HAZUS-MH Estimates: NYC Economic Losses from a Coastal Storm Wind and Storm Surge by County — 100-Year
| Borough | Building Loss | Contents Loss | Inventory Loss | Total |
| Bronx | $1,241,670,000 | $129,840,000 | $500,000 | $1,372,000,000 |
| Kings | $4,843,150,000 | $1,554,360,000 | $42,730,000 | $6,440,250,000 |
| New York | $6,217,760,000 | $3,793,230,000 | $55,920,000 | $10,066,900,000 |
| Queens | $1,563,800,000 | $424,840,000 | $6,860,000 | $1,995,500,000 |
| Richmond | $1,492,070,000 | $443,420,000 | $20,620,000 | $1,956,110,000 |
| Total | $15,358,450,000 | $6,345,680,000 | $126,630,000 | $21,830,750,000 |
HAZUS-MH Estimates: NYC Economic Losses from a Coastal Storm Wind and Storm Surge by County — 200-Year
| Borough | Building Loss | Contents Loss | Inventory Loss | Total |
| Bronx | $187,370,000 | $230,650,000 | $50,050,000 | $468,070,000 |
| Kings | $265,530,000 | $397,900,000 | $9,220,000 | $672,650,000 |
| New York | $336,320,000 | $478,730,000 | $9,300,000 | $824,350,000 |
| Queens | $194,130,000 | $204,700,000 | $5,480,000 | $404,310,000 |
| Richmond | $25,970,000 | $59,080,000 | $6,610,000 | $91,660,000 |
| Total | $1,009,320,000 | $1,371,060,000 | $80,660,000 | $2,461,040,000 |
HAZUS-MH Estimates: NYC Economic Losses from a Coastal Storm Wind and Storm Surge by County — 500-Year
| Borough | Building Loss | Contents Loss | Inventory Loss | Total |
| Bronx | $5,729,860,000 | $933,830,000 | $41,550,000 | $6,705,230,000 |
| Kings | $17,662,450,000 | $5,582,600,000 | $142,510,000 | $23,387,560,000 |
| New York | $18,232,260,000 | $9,083,600,000 | $132,140,000 | $27,447,990,000 |
| Queens | $8,736,340,000 | $2,676,390,000 | $87,350,000 | $11,500,080,000 |
| Richmond | $3,239,540,000 | $1,294,870,000 | $77,050,000 | $4,611,460,000 |
| Total | $53,600,450,000 | $19,571,290,000 | $480,600,000 | $73,652,330,000 |
HAZUS-MH Estimates: NYC Economic Losses from a Coastal Storm Wind and Storm Surge by County — 1,000-Year
| Borough | Building Loss | Contents Loss | Inventory Loss | Total |
| Bronx | $11,710,460,000 | $2,544,220,000 | $43,530,000 | $14,298,220,000 |
| Kings | $23,911,710,000 | $6,189,090,000 | $122,710,000 | $30,223,510,000 |
| New York | $17,219,390,000 | $2,998,670,000 | $15,030,000 | $20,233,090,000 |
| Queens | $19,079,290,000 | $4,678,160,000 | $97,840,000 | $23,855,300,000 |
| Richmond | $2,902,150,000 | $913,240,000 | $46,410,000 | $3,861,800,000 |
| Total | $74,823,010,000 | $17,323,390,000 | $325,520,000 | $92,471,920,000 |
HAZUS Coastal Storms Return Intervals
Source: NYCEM GIS
Infrastructure
Much of New York City’s aging transportation and utility infrastructure is also highly vulnerable to significant damage from coastal storms. Within the transportation sector, subway tunnels, subway stations, passenger car tunnels, and bus depots in low-lying, flood-prone areas are at particular risk. For example, during Hurricane Sandy, the city suffered extensive flooding of subway, PATH, commuter train, and Amtrak tunnels, as well as the Hugh Carey Brooklyn-Battery and Queens-Midtown vehicular tunnels. Disruptions in the commodity supply chain could result in shortages of liquid fuels throughout New York City. Physical damage or loss of power to key distribution terminals, as was experienced during Hurricane Sandy, is also a significant risk.
Vulnerable utilities include aboveground telecommunications and power-distribution infrastructure (power lines and electric substations) that are directly exposed to wind, flooding, falling trees, and flying debris. Underground power and telecommunications are less exposed, but are still subject to flooding in vulnerable locations. An inflow of saltwater can corrode and damage underground electric distribution equipment and transportation infrastructure.21Con Edison Media Relations, “Storm Isaias Outage Is Second Largest in Con Edison’s Long History,” Con Edison, August 4, 2020.
Hurricane winds can impact trees and bring down power lines, causing power outages. In 2020, Tropical Storm Isaias brought down many power lines, causing 257,000 customer outages (NYC and Westchester County). The outages were mostly caused by the high winds downing trees on overhead power lines. This event caused the second largest outage in Con Edison’s history, preceded by Hurricane Sandy, which caused 1.1 million customer outages.22Division of Reliability and Security, Review and Assessment of Electric Utility Performance, New Jersey Board of Public Utilities, State of New Jersey, November 18, 2020.
The table titled Infrastructure and Critical Facilities Located within Storm-Surge Inundation Areas estimates that 35 percent of the total number of critical facilities and key assets in New York City are located within storm-surge inundation areas for Category 1 through 4 storms based on SLOSH modeling. The last column indicates the degree to which specific types of New York City facilities and assets are at risk from storm surge and severe damage during coastal storms.
As shown, all of the City’s 26 power generation plants and 14 wastewater treatment plants are located in storm-surge inundation areas, including 13 wastewater treatment plants in the storm-surge inundation area for a Category 1 storm.23NYC Department of Environmental Protection, NYC Wastewater Resiliency Plan: Executive Summary, NYC Department of Environmental Protection.
Infrastructure and Critical Facilities Located within Storm-Surge Inundation Areas
*Based on airport perimeter — significant surge impact only.
**Active New York City commuter/commercial/recreational ferry landings only (including Ellis and Liberty islands). All landings assumed to be in Category 1 Storm-Surge Inundation Area.
***Determination made by NYCEM and DCP on which assets to include.
****Estimated only. Based on visual review of bridge/tunnel segments with ortho photo. Considered not in a zone if all New York City approaches are fully clear of inundation. Major roads do not include bridge/tunnel spans.
Source: NYCEM GIS
Natural Environment
Coastal storms can have large impacts on natural areas and coastal ecosystems. Significant coastal storms have the potential to erode and harm wetlands and cause barrier islands to narrow or split. Coastal storms can also cause beach and dune erosion, wetland loss, and barrier island breaching that damages or destroys coastal habitats and disrupts migration patterns of terrestrial animals. The loss of natural storm barriers also exposes wooded areas and parks farther inland to the impacts of wind and storm surge. For example, saltwater inundation as result of storm surge on wooded areas leads to tree mortality and lessened health for years following an exposure event. Coastal storms can directly affect the health of the natural environment by contributing to the release of hazardous materials (HAZMAT) or causing overflow from sewers and wastewater treatment plants. Throughout the history of New York City, many industrial facilities have been built along or near the waterfront to facilitate maritime transportation. Even today, many of these low-lying areas are dominated by industrial use.
Coastal storms and related flooding raise the risk of HAZMAT releases from these industrial sites, which could contaminate underground water and soil, which discharge into and further contaminate nearby bodies of water. Certain chemicals may be toxic to species of plants, animals, and invertebrates. Uncontained spills, especially those that impact surface water, can kill or injure plants, fish, and wildlife and cause damage to their habitats and food sources. The remediation of the natural environment after a toxic chemical release poses its own unique challenges and often involves lengthy, costly processes. Large volumes of debris in local waterways, resulting from coastal storms, can also be hazardous to local species. Cumulative impacts from coastal storms can lead to large-scale changes in the population, distribution, and migrations of marine and aquatic species over the long term.
Future Environment
In planning for the potential impacts of future coastal storms, planners and emergency managers must understand how climate change will affect the probability and severity of these storms in or near New York City. When considering the risk from coastal storms, impacts from three potential changes need to be considered: an increase in coastal storm surge as the sea level rises, an increase in extreme hurricane winds, and an increase in the frequency of the most intense storms.
Ocean surface temperatures are projected to increase as the global climate continues to warm, causing storms to intensify. It is unclear exactly how changes to all the climatic variables will affect the behavior of hurricanes in the future; however, climate scientists predict that the frequency of the most intense hurricanes (but not the frequency of hurricanes in general) could increase globally, particularly in the North Atlantic Basin.
Although uncertainty exists as to the exact nature of the change affecting coastal storm systems, scientists predict that the impacts of coastal storms will worsen in the future when combined with the impact of rises in sea level due to climate change. First, as ocean water warms, it expands and increases in volume, causing sea levels to rise. Second, increased average temperatures by climate change cause land glaciers and polar ice caps to melt at a faster rate, which increases the amount of water in the oceans. The sea level off New York’s coast is up to 9 inches higher than it was in 1950 in New York City due to a combination of warming climate and local factors such as land subsidence (sinking).24SeaLevelRise.org, “New York’s Sea Level Has Risen 9″ Since 1950,” SeaLevelRise.org.
The New York City Panel on Climate Change (NPCC) projected the degree of sea-level rise in 30-year intervals. The chart below summarizes their findings for four intervals.25C. Braneon, L. Ortiz, D. Bader, et al., “NYC Climate Risk Information 2022: Observations and Projections,” New York Academy of Sciences, under review.
Projections for Sea-Level Rise in New York City for 2030–2150 (1995–2014 Baseline)
| 10th Percentile | 25th Percentile | 75th Percentile | 90th Percentile | |
|---|---|---|---|---|
| 2030s | 6 in. | 7 in. | 11 in. | 13 in. |
| 2050s | 12 in. | 14 in. | 19 in. | 23 in. |
| 2080s | 21 in. | 25 in. | 39 in. | 45 in. |
| 2100 | 25 in. | 30 in. | 50 in. | 65 in. |
| 2150 | 38 in. | 47 in. | 89 in. | 177 in. |
These rising sea levels around New York City would exacerbate the impact of coastal storms. More extensive damage would occur because a storm of equivalent magnitude would induce stronger storm surges from rising sea levels.
How to Manage the Risk?
New York City takes an integrated approach to managing risk associated with coastal storms. This approach involves a comprehensive plan that includes regulatory, water management, land management, and environmental policies in addition to public education initiatives.
Public-private partnerships and other collaborative efforts have been underway for several years to protect buildings and infrastructure in New York City from the high winds associated with coastal storms. New York City also focuses on increasing public awareness of risks from high winds and flooding during coastal storms, particularly among people living in flood zones and areas of greatest risk.
New York City has formed the new Coastal Resiliency Bureau at the DEP, as outlined in the City’s 2023 PlaNYC climate action plan. The new bureau at DEP establishes central coordination for flood resilience projects and provides New Yorkers with a central repository of information on local flooding events.26City of New York, PlaNYC: Getting Sustainability Done, City of New York, April 2023.
New York City’s Climate Resiliency Design Guidelines (CRDG), currently being applied in a five-year pilot program across 23 City agencies, help inform design and construction of City assets based on exposure to current and future coastal flood risk. Mandated by Local Law 41 (2021), scoring based on the CRDG will be required of all City capital projects beginning 2027.
A wide range of coordinated strategies are employed to cope with and recover from the multiple, varied social and structural consequences of these cyclical coastal natural phenomena. New York City provides a complete, detailed database on the ongoing and planned mitigation activities and projects of dozens of City agencies.