Extreme Weather Toolkit: Heavy Rain and Flooding

Climate change is bringing heavier rainfall extremes and increased, inequitable flood risk to many parts of the U.S. 

For every 1°F of warming the air can hold an extra 4% of moisture, increasing the chances of heavier downpours that contribute to the risk of flash floods. 

The rapid onset of flash floods limits time to get people out of harm’s way. In the U.S., racial minorities and those living in mobile homes are disproportionately exposed to flood risk, especially in the South and in rural areas. 

In the U.S., extreme daily rainfall has become more frequent since the 1980s. Hourly rainfall intensity has also increased since 1970 — by 13% on average across 150 U.S. locations analyzed by Climate Central.

And from 1958 to 2021, the heaviest 1% of rainfall events became 60% and 45% wetter in the Northeast and Midwest, respectively — and 1% to 37% wetter for all other regions in the continental U.S. 

Changes in rainfall from 1988 to 2017 accounted for one-third of U.S. flood damages (about $73 billion) over that same period. And the most intense downpours caused the largest damages. 

The latest IPCC reports indicate that precipitation extremes are likely to increase globally, even in regions with decreasing average precipitation.

Most of the U.S. is projected to see increases in precipitation extremes with 2°C (3.6°F) of  warming.

With high future levels of heat-trapping emissions, U.S. flash floods could also intensify — especially in the Southwest. A recent study suggests that the burdens of an estimated 26% increase in overall U.S. flood risk by 2050 could disproportionately impact Black communities along the Atlantic and Gulf coasts.

Updated: April 2024

Resources

These resources explore the science, trends, and local impacts of heavy rain and flooding in the U.S.

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Climate Matters

Extreme Precipitation in a Warming Climate

Climate change is supercharging the water cycle, bringing heavier precipitation extremes across the U.S.

Climate Matters

Climate Change and Inland Flooding

Flooding is costly, damaging, and deadly. It affects much of the U.S. and is likely to intensify with warming and shifting rainfall patterns.

Climate Matters

Rising Hourly Rainfall Intensity

Hourly rainfall intensity—a key factor in flash floods—has increased since 1970 in 136 U.S. locations analyzed by Climate Central.

Climate Matters

Atmospheric Rivers

Atmospheric rivers bring both vital water resources and deadly hazards—especially in the western U.S.

Climate Matters

Changing precipitation normals

We look at the change in precipitation between the 1991-2020 and 1981-2010 periods, and break down the regional and seasonal patterns across the U.S.

Climate Matters

After the Storm: Damp, Moldy Homes

Extreme weather events fueled by climate change bring health risks—including from damp, moldy homes after storms and floods.

Climate Matters

Wettest Seasons in U.S. Regions

Water supplies, agriculture, and ecosystems all rely on precipitation. Explore seasonal precipitation patterns in U.S. states and regions and see how they’re changing.