Climate Central

May 15, 2025

Extreme Weather Toolkit: Heavy Rain and Flooding

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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 possibility of heavier downpours that can result in flooding. 

As the climate has warmed from 1958 to 2021, the heaviest 1% of downpours have intensified in every major region in the continental U.S., led by the Northeast (+60%) and Midwest (+45%). Extreme daily rainfall has also  become more frequent across the country since the 1980s, and  hourly rainfall rates have increased by 15% on average across 126 U.S. cities analyzed by Climate Central.

This hazardous intensification of rainfall is expected to continue with future warming. With 2°C (3.6°F) of warming, U.S. counties are likely to see an average of 17% more precipitation falling during the heaviest rainfall events. The latest IPCC reports indicate that precipitation extremes are likely to increase globally, even in some regions with decreasing average precipitation.

While increases in heavy rainfall don’t always translate to increases in flooding, since flood risk depends on a number of factors, with high future levels of heat-trapping emissions, U.S. flash floods could also intensify — especially in the Southwest.  In the U.S., people of color and those living in mobile homes are disproportionately exposed to flood risk, especially in the South and in rural areas. A recent study suggests that the burdens of increased U.S. flood risk by 2050 could disproportionately impact Black communities along the Atlantic and Gulf coasts.

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

Updated: May 2025