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Climate Change Challenges

Extreme Rainfall

Climate change will cause more frequent and intense rainfall in both coastal and inland areas.

Impacts of stormwater flooding will not be experienced equally across NYC.

Extreme rainfall events, sometimes called “cloudbursts,” occur when a large amount of rain falls in a short time. Extreme rain can cause flooding in low-lying areas that have poor drainage and insufficient stormwater infrastructure systems. This can cause flooding throughout the City, even in inland neighborhoods. Rain-driven flooding can occur suddenly and intensely, but flood conditions may subside more quickly compared to coastal surge flooding.

Extreme rainfall events will increase in number and severity in the future because of climate change. By the end of the century, the city could experience as much as 25 percent more annual rainfall than today, and 1.5 times as many days with more than one inch of rain. Additionally, as sea level and groundwater tables rise, stormwater will drain more slowly and contribute to flooding.

The maps show a range of flood scenarios to help New Yorkers understand how stormwater flood patterns may change over time.

Extreme Rainfall Impacts

Extreme rainfall events pose significant health risks for New Yorkers. New Yorkers can face risks of drowning, particularly those living in basement apartments. During Hurricane Ida in 2021, , flash flooding caused by extreme rainfall resulted in at least 13 deaths in New York City. A majority of those who died drowned in basement apartments and at least one was trapped by floodwaters while driving. Older New Yorkers and those with limited mobility face challenges evacuating flooding areas, and New Yorkers who are not English-proficient may not receive emergency information that is in their language or that is culturally appropriate. In particular, undocumented New Yorkers and those experiencing homelessness may be hardest to reach due to limited networks and potential inability or reluctance to access services. Stormwater flooding can also trigger new mental health challenges in a community, given that these episodes often cause high anxiety and stress. Extreme rainfall can even cause sewers to overflow, exposing New Yorkers and natural systems to contaminated water.

When water is trapped in houses or buildings after extreme rainfall, residents could be at risk to mold exposure. Those risks are even greater for lower-income residents living in substandard housing.  Additionally, New Yorkers needing home meal delivery or home health care may miss meals or treatment if extreme storms prevent caregivers from accessing their homes or locating them in temporary housing and may not be able to get to medical facilities affected by flooding.  Residents who require power for medical care equipment or to refrigerate medication are placed at risk during power outages.

Low-income residents are likely to have fewer financial resources to prepare for or respond to flood events, and some affordable housing is highly exposed to flood risk. Low-income homeowners may also struggle financially after a disaster if they do not have the funds to pay for needed home repairs. Renters, particularly low-income renters, are likely to have less control over their home’s rehabilitation and may not be able to recover damaged personal property.

Extreme rainfall flooding can limit how New Yorkers move around and their ability to participate in the economy. Extreme rainfall flooding can make some roads temporarily unpassable, limiting commutes, deliveries to businesses, and daily life.  Given more dangerous road conditions, cars and buses can experience travel disruptions. Rain-driven flooding can also prevent residents from accessing parked vehicles and in public garages. Below-ground transportation including subway stations can flood.

Extreme rainfall can impair critical community infrastructure like schools, libraries, spaces for youth and senior services, and even cultural sites. New York’s immigrant communities face unique barriers.  Twenty-five percent of New Yorkers who are not English-proficient and they may not receive emergency information that is culturally appropriate or in their language.

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