The winter months in New York City subject residents to prolonged periods of extremely cold temperatures and various storms that sometimes deliver large amounts of snow, ice, sleet, freezing rain, and strong winds.
The number or absence of storms per season, the amount of snow from each storm, and prolonged periods of extreme cold can affect people, buildings, infrastructure, and the economy. Hazardous wintry conditions also induce dangers like traffic accidents, power outages, hypothermia, and frostbite.
In the future, climate change could cause winter weather to be warmer, the length of New York City’s snow season to decrease, and snowfalls to become less frequent, leading to “snowless” winters. However, despite these overall climate trends, individual winter weather events in New York City will still have the potential in the future to deliver as much snow and snow cover as they do today.
What is the Hazard?
Extratropical cyclones, the most frequent type of storm in the Northeast, commonly cause rain, snow, and wind, creating severe winter storms that threaten New York City.
Temperature differences between the subtropics and the polar regions cause these frontal storm systems. The storm’s surface wind strength is primarily determined by surface pressure gradients created between the storm’s low pressure and the surrounding area of high pressure.
Subgroups of extratropical cyclones include Nor’easters, winter storms, blizzards, and bomb storms (storms that intensify rapidly). In addition to storms, periods of extremely cold temperatures also present a risk to New York City throughout the winter.
Winter Weather Types
Winter Storms Creating Snow and Ice Hazards
According to the National Climatic Data Center, New York City averages 24.4 inches of snowfall annually. Heavy snow, one of the primary winter hazards affecting New York City, is defined as either a six-inch-or-more accumulation of snowfall within 12 hours or less, or an eight-inch-or-more accumulation within a 24-hour period.
The chart below illustrates the correlation between snowfall and climate change in New York City. While the city averages more than 20 inches of snow annually, there has been a noticeable trend of increased days without snowfall accumulation in recent years. This trend is highlighted by the years 2020 and 2023, which rank first and second respectively in the graph for the most days without snowfall. It’s noteworthy that on February 1, 2023, New York City ended a 328-day snowless streak, just shy of the December 15, 2020, record of 332 consecutive days without accumulating snow.i These close intervals underscore the significant impacts of climate change on the patterns of winter weather in the city, emphasizing the need to incorporate these changes into future weather analyses and planning.
Several types of winter-weather conditions have the potential to affect New York City.
Winter Weather Definitions
|Precipitation in the form of ice crystals that form directly from water vapor freezing in the air.
|Pellets of ice composed either of fully or partially frozen raindrops, or refrozen, partially melted snowflakes.
|Snow falling at varying intensities for brief periods with accumulations of one inch or less.
|A combination of conditions prevailing for three hours or more: Sustained winds or frequent gusts of 35 mph or more. Blowing snow may reduce visibility to one-quarter of a mile.
|Intense, brief periods of moderate-to-heavy snowfall, accompanied by strong, gusty surface winds and possibly lightning, with a risk of significant snow accumulation.
|A snowstorm accompanied by thunder and lightning, can occur over intense low-pressure systems or other similar conditions of relatively strong instability and abundant moisture.
|Freezing rain with potential accumulations of one-quarter of an inch or more.
|A low-pressure system that intensifies very rapidly with a fall in pressure of at least 24 millibars in 24 hours.
The hazards inflicted upon New York City by winter storms can be significant. Snow and ice hazards can compromise public safety and health and prevent the normal, day-to-day functioning of infrastructure and services. Snow accumulations that block roadways, public transit infrastructure, and sidewalks impede people and vehicles’ mobility and access to critical services and places of work. Snow accumulation is hazardous when it damages overhead power and telecommunications lines, and its weight causes trees and limbs to fall onto roofs and vehicles.
All types of wintry precipitation – snow, sleet, and freezing rain – contribute to hazardous travel conditions. However, freezing rain is considered among the most treacherous since it falls initially as rain but freezes on contact with a surface, forming a glaze of ice.
Ice storms present potentially greater hazards for infrastructure in New York City than heavy snowfall because ice storms develop quickly and have a greater chance of downing overhead power and telecommunications lines, leaving New Yorkers without power and communications. Ice accumulation is a hazard that makes walking and driving extremely dangerous, makes roads impassable, and even affects commuter train rail beds and switches in the mass transit system.
Ice severity can be assessed using the following index:
The Index serves as a vital tool for rating the intensity of ice storms, akin to the role of the Enhanced Fujita Scale for tornadoes and the Saffir–Simpson Scale for hurricanes. It is a forward-looking scale, uniquely designed to predict the potential damage of ice storms days in advance. This includes assessing the expected footprint of the storm, the anticipated ice accumulation, and the likely damage to human-built structures, particularly exposed overhead utility systems like power lines. Prior to the development of this hazard scale, there was no such index available to forecast the impact on overhead utility systems and the possible duration of outages due to freezing rain and ice storm events.
An extreme cold event typically involves an extended period with temperatures at or below 32°F. These extended periods of subfreezing temperatures commonly occur in New York City between December and March. Although wind gusts and frigid temperatures often accompany winter storms, extremely cold temperatures can occur in New York City independent of these other types of winter weather events.
As the temperature drops and wind speed increases, heat drains from people’s bodies more rapidly than normal, creating a “wind-chill effect” that can make people feel even colder than the actual temperature.
This National Weather Service (NWS) wind-chill chart shows the temperature that a person feels on their exposed skin due to the combination of falling air temperature and increased wind speed. As shown, hazard of frostbite increases as people’s exposure to freezing temperatures and bitter wind increases.
When winter weather conditions warrant, the NWS issues wind-chill advisories or wind-chill warnings for the New York City region. NWS issues an advisory when wind-chill values are expected to fall to between 24°F and minus 15°F. NWS issues a wind-chill warning when values are expected to fall to minus 25°F or below.
The severity of a winter storm depends on the temperature, its wind speed, the nature of associated precipitation, its rate of accumulation, and its timing. For example, a storm that occurs in early winter, when leaves are still on the trees, has the potential to cause more trees and power lines to topple as the extra snow and ice accumulate on the tree leaves or poles and weigh them down.
El Niño and La Niña are two parts of a natural climate cycle that affect winter weather — the warm and cool phases of a recurring climate pattern across the tropical Pacific. The pattern can shift back and forth irregularly every two to seven years. Each phase can trigger predictable disruptions of temperature, precipitation, and winds that have the potential to intensify winter weather affecting New York City.
Historically, El Niño events are more likely to intensify warm-weather events in the Northeast, whereas La Niña events are more likely to affect colder weather events there. Predicting the potential impact of El Niño and La Niña is complicated due to the variability of other natural weather phenomenon that affect temperature and weather in the Northeast, such as the cycles of the North Atlantic Oscillation and Artic Oscillation.
Winter storms are classified by meteorological measurements and their societal impacts. The Northeast Snowfall Impact Scale (NESIS), a post-event classification, characterizes and ranks high-impact Northeast snowstorms – those with large areas of snowfall accumulations of 10 inches and more – on a scale of one to five.
The National Climatic Data Center developed the NESIS scale to indicate the impact that Northeast snowstorms might have upon the transportation systems and economy of the region and potentially the rest of the United States. The NESIS index is different from other meteorological indices, because it incorporates population data and meteorological measurements to assess a storm’s overall societal impact.
NESIS scores are derived from the size of the area affected by the snowstorm, the amount of snow accumulation, and the number of people living in the path of the storm. Snowfall and population factors are combined into an equation that calculates a NESIS score, which is associated with a range of storms, classified from small to extreme. Storms generating heavy snowfall over large areas that include major metropolitan centers would generate raw scores with the highest values.
The raw score is then converted into one of the five NESIS categories — Notable, Significant, Major, Crippling, and Extreme.
Since 1872, New York City has experienced 15 snowstorms with snowfall totaling 16 inches or more. According to NESIS, five storms were crippling, four were major, and one was significant. Data from the remaining five historical snowstorms did not generate a sufficiently high value to qualify for a NESIS rank.
|Total Snowfall (In)
|January 2016 Blizzard “Winter Storm Jonas”
|Extreme Cold Event
|Heavy Snow Event
|Heavy Snow Event
|North American Blizzard of 2006
|North American Blizzard of 2003
|Extreme Cold Event
|Heavy Snow Event
|Heavy Snow Event
|December 2010 North America Blizzard “Christmas Blizzard”
|High Wind Event
|Blizzard of ’78
|The Blizzard of ’88
Winter storms are frequent occurrences in New York City. Based on historical frequency, New York City is likely to experience a winter storm with snow accumulation of 16 inches or more approximately once every nine years.
Historically, there are only a few reported instances of thundersnow in New York City. However, the most recent thundersnow event occurred here on March 7, 2018. Thundersnow events are less likely to occur in extremely cold winter months than in warm-weather months.
According to the New York City Panel on Climate Change, days below freezing have been declining at a rate of 2-3 days per decade at Central Park and LaGuardia stations. The last 30 years have experienced an average of less than 70 days per year below freezing, down from a 1900-1929 level of 87 days.
All areas of New York City are susceptible to winter storms. However, snowfall totals can vary widely across the city during these events. For example, during the February 9, 2017, winter storm, snowfall ranged from 8.5 inches in Staten Island to 12.5 inches in the Bronx.
|Variations in Measured Snowfall Across NYC, Winter Storm Niko (2017):
New York City generally experiences less severe cold than other places in the greater metropolitan area for two reasons — the urban heat-island effect and its proximity to the ocean. Areas near shorelines often have slightly warmer temperatures during colder months than inland areas. However, even with warmer temperatures in coastal areas, strong winds near the shore can still create hazardous wind-chill conditions that affect residents.
Neighborhoods in New York City with relatively low population density, lots of trees and natural ground cover, and low amounts of heat-absorbing asphalt typically remain a few degrees cooler than other neighborhoods in summer months, but this warming effect is less pronounced during colder winter months.
New York City has experienced a range of major winter storms from 1798 through 2023 For more information on winter weather events, use the Hazard History and Consequence Tool, an interactive tool developed for this website.
Over the last 25 years, three winter snowstorms and blizzards were sufficiently damaging to earn presidential disaster declarations for New York City and the surrounding region:
- The Blizzard of 1996 in January 1996
- The President’s Day Snowstorm II in February 2003
- The Blizzard of 2010 in December 2010
Of the top five snowstorms recorded in New York City’s history, the Blizzard of 2016 broke the record for total snowfall accumulation in January 2016. As the top-five list shows, record snowfall accumulations in New York are not confined to recent years.
Although the Blizzard of 2016 is remembered for the hazards caused by over 30 inches of snowfall, a secondary hazard created by this winter weather event is worth noting. This January winter storm, also called Winter Storm Jonas, occurred during spring tide, which contributed to moderate storm surge and flooding in coastal areas throughout the region.
In December 2022, the Jamaica Bay area of New York City experienced a significant weather event: a Southeaster storm associated with the King Tide. Unlike the common perception, Southeaster storms are a type of cyclone, similar to Nor’easters. The distinction lies not in the storm’s rotation, but rather in its trajectory towards the Northeast. Southeasters approach from over New York, impacting the region from the west, and thus, their winds hit areas like Maine from the southeast. Often, the winds from Southeasters can be even stronger than those from Nor’easters.ii During this specific event, the Southeaster coincided with the King Tide, leading to exceptionally high tides resulting from the combined gravitational pull of the sun and moon. This unusual alignment contributed to significant storm surge and flooding in both coastal and inland areas around the Jamaica Bay region, compounded by a subsequent drop in temperatures. The provided charts and maps detail the tidal flooding impacts in this area, emphasizing the unique and potent combination of a Southeaster with a King Tide.
Flood sensors and tide gauges are organized in the graphs below. Given the case study below as a winter event, we wanted to focus on the rainfall and flooding impacts of a hazard that may seem subsidiary to normal expectations. FloodNet provides flood sensor data. This allows our team to view granular inland and coastal flooding data. As we see from the example below, we gleaned greater insight into how such an event can affect inland areas by causing, in some areas, more than 40 inches of water above normal levels. As for tide gauges provided by the Stevenson Institute, we can track significant spikes and trends throughout the event. Regardless of our previous notions of winter weather, we want to consider all potential impacts, especially flooding, climate change, and rising sea levels.
Although the surge associated with the winter storm, it demonstrates that the accumulation of water from coastal storm surge, sea level rise, and tide levels during a winter storm can flood coastal areas and simultaneously bury the city in massive, unprecedented amounts of snow.
In addition to climactic effects, the surge caused various consequences across the city, specifically Queens Community District 14 (Arverne, Broad Channel, Edgemere, Far Rockaway, Jamaica Bay), which had 161 households with reported damage, out of 261 total citywide.
What is the Risk?
During the winter, snow and ice accumulations and extremely cold temperatures can pose risks to public health, public safety, buildings, infrastructure, and the New York City economy.
Winter storms are also especially hazardous for people who work outdoors, people experiencing homelessness without shelter, people with inadequate heat at home, children traveling to school, seniors, and other vulnerable populations.
Extreme cold, wintry conditions, and wind gusts all pose health risks to even to the most intrepid New Yorkers – increases in cold-related illnesses, such as hypothermia and frostbite, and worsened chronic health conditions for people suffering from respiratory or cardiovascular disease.
Hypothermia occurs after a person is exposed to cold temperatures for an extended period of time and their body loses heat faster than heat can be generated, causing a drop in their body’s temperature. Symptoms include shivering, fatigue, loss of coordination, blue skin, dilated pupils, slow pulse and breathing, and loss of consciousness, which potentially could be fatal.
Frostbite happens when the body’s outer tissue freezes, affecting a person’s nose, ears, cheeks, chin, fingers, or toes. Symptoms include numbness, tingling, stinging, aching, and skin discoloration. Frostbite can cause permanent damage to whichever part of the body is affected and in severe cases, may require amputation.
From 2005 to 2014, New York City recorded an average of 180 treat-and-release hospital emergency department visits and 240 hospital admissions associated with cold-related illness (i.e. hypothermia and extremity injuries), and 15 cold-related deaths (with outdoor and indoor exposures) during the cold season (October through April). Additionally, there were typically 15 cold-related deaths each year, accounting for both outdoor and indoor exposures. However, in 2020, there was a notable increase, with 23 deaths in NYC directly attributed to cold stress. It’s important to recognize that these figures only include deaths explicitly cited as cold-related on death certificates.iii Data by year on cold-related deaths and illnesses are available here. In addition to direct cold-related illness, low temperatures can exacerbate chronic conditions like heart conditions, asthma and other respiratory diseases, sometimes also leading to death (i.e. excess mortality).iv In addition, living without adequate heat or power can impact mental health, with increased symptoms of anxiety or depression.vvi
Spending time in the cold, indoors and outdoors, can be dangerous. Those most at risk include people who are homeless and not protected in shelters.vii In addition, people who live in a home without heat. If a home lacks heat during winter months, residents sometimes resort to heating with alternative heat sources such as stoves, ovens, or charcoal grills, which pose fire and carbon-monoxide poisoning risks. Space heaters, if poorly made or used improperly, also pose fire risks.
The risk of living without heated sheltered affects vulnerable New Yorkers including those who are or experience:
- Older Adults
- Certain medical conditions
- Serious mental health conditions or developmental disabilities
- Mobility disability
Icy conditions during winter months often contribute to falls or other injuries for anyone venturing outdoors, but older adults are particularly vulnerable to slips and falls on icy sidewalks. A range of other injuries related to snowy, icy conditions are possible, including back injuries from strenuous snow shoveling. Being outside in snow or ice storms is especially hazardous for outdoor workers, people who are experiencing homeless, and other at-risk populations.
Carbon monoxide (CO) poisoning is another risk during winter weather. Home appliances, notably gas kitchen ranges and space heaters, as well as boilers, pose a risk of carbon monoxide emission if they are not properly maintained and ventilated. Although carbon monoxide poisoning can occur at any time of the year, the danger is greater during winter months and periods of extreme cold. Running vehicles inside garages to avoid the cold is dangerous, since carbon monoxide can accumulate to fatal levels inside a person’s car, garage, or even a home with an attached garage. In addition, running a vehicle warmth can also be extremely dangerous if the tailpipe is blocked by snow. Lethal amounts of CO can quickly accumulate (within minutes) inside the vehicle.viii For example, there were 4 CO deaths related to snow blocking tailpipes in the winter in NYC from 2005-2013.ix
Trees and power lines that are downed during winter storms can put people at risk. Power outages are often caused by winter storms when trees topple onto power lines or ice weighs down power lines and brings them down. Accidental contact with a downed power line can result in electrocution.
Power outages trigger a number of problems and increase health risk for people living without backup power. Anyone that depends on electric medical equipment to sustain them is at risk if the power goes out.
Winter storms can disrupt utility supplies that provide heating to residents or tenants. If a winter storm interrupts the supply of fuel oil, natural gas, steam, or electricity to building heating systems, occupants’ health is at risk from the drop in building temperatures. Occupants could suffer from hypothermia or frostbite. If a person suffers from a chronic illness, such as asthma or another respiratory disease, their condition be exacerbated. Residents who use candles as their light source during power outages are at increased risk from setting accidental fires.
Prolonged extreme cold temperatures can put an additional operational strain on building boilers. Heating failure particularly critical during winter weather because snow and ice could cause issues with cellar access or deploying emergency repair teams to fix boilers. Use of space heaters when there is inadequate home heat can also increase fire risk. For example, a malfunctioning space heater started a 2022 fire in the Bronx that killed 17 people. x
Home heat and/or power loss can happen during winter storms, but residents’ options to move are limited, particularly if they prefer to stay in their own neighborhood. Because of New York City’s limited supply of available housing, there are few places to house displaced residents. The threshold for a housing emergency is a 5% rental vacancy rate, but the 2021 New York City Housing and Vacancy Survey (NYCHVS) cites only a 4.54% rental vacancy rate.
Icicles and snow falling from buildings during winter can injure pedestrians, damage vehicles, and disrupt transportation. Streets sometimes must be closed for safety reasons. Periods of heavy snow and ice can disrupt the city’s infrastructure and services; strand commuters and other travelers; interrupt the flow of and access to food, medicine, and other essential supplies; and constrain emergency response and delivery of medical services.
Every category of wintry precipitation contributes to hazardous travel conditions, including freezing rain, which is the most treacherous. The risk of traffic accidents is more likely during winter storms in New York City. Even small accumulations of ice on roadways can cause accidents, injuring motorists, bicyclists, and pedestrians and potentially causing fatalities.
Even on the street, if a parked driver tries to stay warm in their car by running their engine and doesn’t realize that snow is blocking their vehicle’s tailpipe, carbon monoxide poisoning could occur quite rapidly and cause death.
During and after major winter storms, businesses may see short-term revenue and productivity losses. Government entities may experience budget shortfalls as they take necessary actions to deal with unanticipated winter weather events.
Since New York is a global travel hub, winter storms that trigger flight delays and cancellations have the potential to disrupt travel on a global and national scale, with economic consequences for the flow of international and domestic business, conferences, meetings, and events.
In dealing with the consequences of winter weather, the New York City Departments of Sanitation (DSNY), Transportation (DOT), and Parks and Recreation (NYC Parks) may bear additional expenses for snow and ice removal and for pothole repair. The City’s budget for snow removal is based on a rolling five-year average of actual expenditures. Since 2020, the City has budgeted close to or exceeded $12 million for every inch of snow pushed to the curb for increased snow events.
According to the Independent Budget Office of NYC, expenditure increases over time partially reflect the rising cost per inch to plow snow. The cost-per-inch measure does not account for year-to-year variability. Because DSNY mobilizes in advance for a predicted storm, even snowstorms that do not materialize can be costly.
In 2020, just 5 inches of snow fell on the city, well below the National Oceanic and Atmospheric Administration annual snowfall average for Central Park of 26 inches. With little snowfall, fixed costs such as training, maintenance and purchases of salt and other supplies were spread over fewer inches of snow, resulting in a cost of $12 million per inch— more than four times the average annual cost since 2003.
Winter storms can have a dramatic impact upon New York City’s infrastructure, creating risks for residents, emergency responders, commuters, drivers, and travelers. Snow-covered streets can cause traffic accidents and impede emergency access. Fire hydrants buried in snow can slow down FDNY response times.
Ice accumulation affects roads, rail beds, and mass transit rail switch systems, creating difficult and dangerous conditions for commuters, commercial vehicle drivers, and other travelers. Bridges and overpasses are especially dangerous, because elevated roadways freeze before other road surfaces. Transit railways can break or crack under stress if they are subject to sustained extreme cold temperatures.
Freezing temperatures and repeated freeze-thaw cycles often cause potholes and increase the size of pre-existing road damage, which pose a risk of damaging vehicles and causing traffic accidents as vehicles unexpectedly swerve to avoid them.
During winter months, DSNY spreads rock salt on roadways to melt snow and ice. The thaw phase of freeze-thaw cycles can dissolve rock salt, creating the risk that this salty water seeps into manholes, corroding and short-circuiting underground electric cables. This seepage is a risk that could result in service interruptions, manhole fires, or in rare cases, explosions.
Power lines are built to withstand one-quarter of an inch of ice accumulation; however, nearby tree limbs can fall due to high winds, knocking out power and phone lines, even when ice accumulation is minor or nonexistent.
Winter weather also has an impact on New York City’s building stock. Some buildings accommodate drops in temperature better than others due to three factors — the type and size of windows, the amount of air escaping through cracks and leaks in the walls, and the amount of wall and roof insulation. Older buildings constructed according to less-stringent building codes are more vulnerable to drafts because leaks in the walls, windows, and doors are more likely. Buildings constructed according to more recent construction codes, standards, and the NYC Energy Conservation Code have more effective thermal protections.
Poorly maintained vacant wooden buildings, which constitute only a small portion of New York City’s total building stock, are most at risk for winter damage. New York City rarely experiences building collapses or structural damage due to snow and ice; however, it is possible. If a building’s roof structure is not properly maintained, snow accumulation can cause damage, leaks, and roof collapse.
The potential for roof damage depends on a combination of several factors — the type of snow, frequency of snow events, and extreme cold temperatures. For example, a big layer of wet snow, which is heavier than normal snow, puts more stress on roof structures. More frequent snow events in combination with extreme cold temperatures may cause higher snow accumulation and increase weight on a roof.
Decaying wood or brick masonry can also be made worse by winter weather. Standing water in masonry cracks could turn to ice that leads to damage on the building’s façade.
Frozen or burst pipes, a common occurrence during cold spells, may interrupt water and gas supplies and damage drainage systems.
The two greatest risks posed by winter weather to New York City’s natural environment are ice accumulation and snowmelt runoff.
When snow and ice melts, the runoff flows into New York City’s sewer system. Risk occurs if the volume of runoff combined with the volume of sanitary waste exceeds the capacity of the City’s wastewater treatment plants to handle the excess volume. A combined sewer system collects rainwater runoff, domestic sewage, and industrial wastewater into one pipe. Normally, it can transport all of the wastewater to a treatment plant. Sometimes the amount of runoff exceeds the capacity of the system. When that happens, untreated stormwater and wastewater flows into nearby waterbodies, creating risk of temporarily contaminating local waterways.xi
NPCC3 analyzes trends in the number of days below freezing (a day where minimum temperatures reach less than or equal to 32 °F) in a year and in the number of cold days (a day with minimum temperatures less than or equal to the 10th percentile of daily minimum temperature of a given year) between 1900 and 2020 at the Central Park weather station.xii
In recent decades, New York City’s Central Park and LaGuardia weather stations have recorded a notable decrease in days with below-freezing temperatures, with a reduction rate of approximately 2-3 fewer days per decade. When examining the broader period from 1900 to 2017, the data shows that the 10th percentile threshold for cold days was set at 24.1 °F. Over this period, there’s been a steady decrease in the frequency of these cold days, averaging a drop of about 1.5 days per decade. This trend has led to a significant decrease in the number of cold days: there were about 17 fewer cold days annually in 2017 compared to 1900. Comparatively, while there was an average of 87 days below freezing per year between 1900-1929, this number has declined to an average of only 67 days in the most recent 30-year period, highlighting a clear shift in temperature patterns over time.xiii
This indicates that snow accumulation will last for shorter timeframes than it currently does. However, it should be kept in mind that these are projected changes in decadal averages. Individual winters could still have as much snow and snow cover as our current climate, though the projections show that these types of winters will occur less frequently. The projected changes to the risk from extreme ice storms as the climate modifies over time is still uncertain.
How to Manage the Risk?
Strategies for managing winter-weather risks include placing regulatory controls on building design, strengthening building maintenance and retrofits, adding infrastructure protections, putting environmental controls in place, and continuing efforts to help New Yorkers prepare for and respond to severe weather events. For example, NYC has laws mandating landlords to provide heat to tenants in the winter.
Regulatory requirements to mitigate risk from winter weather take the form of increasingly robust engineering requirements in New York City’s Construction Codes and Energy Conservation Code (ECC) that require designs for new buildings to conform to standards that enhance their ability to withstand winter storms and extreme cold, specifically:
- Roofs must be able to withstand snow load (the weight of snow on the roof) and snowdrifts caused by parapets on adjacent buildings.
- Windows must provide thermal protection and buildings must be insulated against extreme cold.
Snow load is a moderate concern in New York City. As early as 1899, the New York City Building Code specified minimum design loads (the weight a roof can hold), load combinations, and procedures to determine snow loads. New York City’s Department of Buildings (DOB) determines snow loads based upon regional climate values for ground snow load that incorporate thermal factors for heated and unheated buildings.
In 2022, the DOB revised the Building Code to follow the most recent national standards for determining snow load, snowdrift loads, and sliding snow loads.
New York City’s construction codes apply to newer buildings any time they undergo substantial change. The DOB also plans to adopt a code specific to existing buildings based on the International Existing Building Code, which is intended to simplify building upgrade regulation and help streamline permitting for resiliency improvements.
Building Maintenance and Improvements
Regular inspections that encourage ongoing maintenance and encouraging retrofitting so that buildings will better withstand winter weather are two strategies to help protect buildings from extreme cold and heavy snowfall.
The DOB considers regular maintenance and repair essential to protect residents and workers from the hazards of winter weather, and encourages periodic inspection to identify when and where repairs are needed.
Building maintenance activities that New York City encourages are:
- Regularly inspecting building elements including parapets, cornices, window lintels, exterior walls, and roofs
- Clearing roofs and overhangs of snow and ice, and cleaning gutters and roof drains before and after snow or ice storms
- Regularly inspecting roof structure for wood rot
- Inspecting and repairing all wood that has rot (especially when rot is close to outside walls)
- Repairing sagging ceilings so they can better withstand snow load
- Replacing all damaged roof joists.
Building Retrofits and Upgrades
Retrofits and upgrades that use higher-performing building materials help buildings retain heat and better withstand severe winter weather.xiv
High-Performing Building Practices and Materials
Recommended measures include:
- Caulking air-seal doors and windows
- Installing insulation and high-performance windows, such as multi-paned windows with reflective coatings that lower heat loss and potentially reduce heating costs
- Understanding that insulated walls retain building heat better than glass
- Protecting internal building infrastructure by fitting exposed pipes with insulation sleeves or other wrapping to slow heat transfer
- Sealing cracks and holes in outside walls and foundations near water pipes with caulking
- Adding insulation indoors or a new exterior layer
- Caulking and sealing air ventilation systems to eliminate drafts.
- Adding a backup generator is a good insurance measure for old and new buildings to reduce risk from possible power outages caused by winter storms. However, generators should never be run indoors and should be placed well away from doors and windows.
Protecting Infrastructure and Equipment
A promising strategy to mitigate risk from winter weather is the use of alternative pavement materials to accelerate snowmelt on streets and sidewalks. A recent study suggests that using permeable pavements noticeably improves the acceleration of snow and ice melt and reduces the need for snow plowing.
This solution would reduce New York City’s reliance upon spreading salt, deploying armies of snowplows, and using chains on vehicle tires, which all damage city streets. Implementing strategies to enhance the City’s ability to clear paved areas more quickly would also reduce the number of winter traffic accidents and improve access for emergency responders.
The New York City Department of Environmental Protection (DEP) is planning demonstration projects to monitor how well permeable pavement materials accelerate snow and ice melt at three locations. The projects are required by Local Law 80 (enacted in 2013), which directs DEP to study alternative roadway and sidewalk materials. Their study will examine:
- Various types of permeable materials
- Expected costs
- Ease of installation
- Material performance
- Absorption rates
- Long-term maintenance requirements.
Another complementary strategy relies on using green infrastructure – such as bioswales (landscape features that collect polluted stormwater runoff, soak it into the ground, and filter out pollution). and green roofs – to capture ice and snowmelt so that it does not reach and overwhelm wastewater treatment plants, which leads to raw sewage discharged into water bodies in and around New York.
The DEP’s NYC Green Infrastructure Plan employs many initiatives to help the City achieve compliance with federal water quality regulations.
A very simple measure for protecting infrastructure is deployed by the MTA. To protect its trains from risk during winter weather, the MTA stores trains underground when forecasts predict temperatures dipping to 10°F below zero, ice storms, icy conditions, or more than five inches of snow.
Tree pruning and tree maintenance strategies lower the risk that the weight of snow and ice will break tree branches and take down power lines during winter months.
NYC Parks’ Forestry Division oversees block pruning, which requires all street trees on a block to be pruned. Contractors perform this service on a seven-to-eight-year schedule. The Forestry Division also prunes trees in city parks.
To maintain reliable service, the city’s major utility, Con Edison, manages a tree maintenance program that trims branches along the right of ways to ensure that trees do not encroach upon power lines during icy winter conditions.
As for energy usage, a winter “peak” will likely occur once 30 to 40 percent of citywide building area has been electrified. That isn’t anticipated to happen statewide until after 2035, but parts of the city will flip their peak season soon.xv
New York City prioritizes helping the public understand how to prepare for and respond to winter weather events. The city engages in two types of communications initiatives — communicating with the public immediately before and during a winter weather event and longer-term educational initiatives to prepare households and property owners.
Immediate communication initiatives when a winter weather event threatens and occurs include:
- Sending emergency alerts prior to severe winter weather events, taking care to target populations with disabilities, access, and functional needs, creating and distributing multi-lingual communications, and reaching out to people who are homeless.
- Sending weather notifications to property owners, contractors, and developers, to advise them of preventative actions they can take to protect property from a winter storm before it hits, such as clearing gutters and removing snow and/or ice from roofs.
- For major storms or prolonged periods of extreme cold, coordinating with multiple City agencies to communicate an accurate, consistent message about weather conditions and what New Yorkers can do to prepare for it. Severe weather events may require mayoral press conferences.
- Utilizing the widest number of media channels for communications — social media, press releases, notifications to elected officials, and emergency alert systems. Social media channels are highly effective in providing New Yorkers with real-time updates as weather conditions worsen or improve.
- To prepare for hazardous winter weather, communicating and promoting assistance that New York City provides to residents. For example, the Home Energy Assistance Program (HEAP) helps qualifying residents to heat their homes.
New York City issues a Cold Weather Alert to the public whenever wind-chill, or air temperatures are forecasted to fall below 32°F between 4 PM and 8 AM. Upon the issuance of a Cold Weather Alert, the City will increase its outreach to the homeless population. The New York City Police Department (NYPD) monitors the city for homeless individuals and transports them to shelters run by New York City’s Department of Homeless Services (DHS) or to city hospitals as necessary. The Metropolitan Transportation Authority also monitors areas in and around stations in the transit system to identify individuals that need shelter and to notify appropriate agencies that can help.
New York City Emergency Management (NYCEM) takes the lead on other winter-storm communications. Notify NYC is the City’s official source of information about emergency situations, including severe winter weather events. NYCEM sends notifications to more than half a million subscribers and Twitter followers.
NYCEM’s Advance Warning System works through agencies and organizations that serve populations with access and functional needs to reach those segments of the city’s population. NYCEM uses email, conference calls, and a website to target and deliver information about weather conditions to individuals with special needs if an impending hazard event puts them at risk. The system is frequently used when winter storms or extended periods of extreme cold are forecast.
The best way for New York City to keep its residents safe from winter weather events over the long term is to undertake initiatives to:
- Help the public learn how to prepare for severe winter weather events.
- Help homeowners learn how to maintain buildings to reduce heat loss, roof leaks, and roof collapses.
- Help households to understand the potentially lethal dangers of carbon monoxide poisoning that gas appliances in their homes can cause.
NYCEM’s Ready New York: Preparing for Emergencies in New York City identifies steps households can take to prepare for prolonged cold weather and winter storms, including the recommended safety precautions for home heating equipment. The Ready New York Reduce Your Risk Guide explains how New Yorkers, particularly homeowners, can reduce risks related to winter weather.
DOB issues inclement weather advisories to advise property owners, builders, and contractors on the precautionary steps they should take to prepare for winter storms, such as clearing snow and ice from roofs, overhangs, and gutters, tying down and securing material and loose debris at construction sites; covering electrical equipment to minimize its exposure to the weather; and securing netting, scaffolding, and sidewalk sheds. Additionally, NYC Housing Preservation and Development investigate reports of inadequate heat or hot water.
The DOHMH website presents information about carbon monoxide poisoning that covers its causes, its symptoms, and recommended preventive measures. A brochure developed jointly by DOHMH, New York City’s Health and Hospitals Corporation, and the NYC Poison Control Center explains how to prevent carbon monoxide poisoning. In addition, DOHMH provides general preparedness information about preventative measures to take to lessen the impact of winter and cold weather.
DOHMH conducts outreach to the general public, community organizations, and services agencies to encourage everyone to check on clients, neighbors, family, and friends who may be at increased risk during winter weather. DOHMH outreach includes social media posts, workshops and training sessions, and direct electronic communications to partners.