Climate change is expected to increase both the amount and frequency of extreme rainstorms in Durham. Warm air can hold more moisture than cooler air, leading to more extreme rain, snow or hailstorms. The large amount of rain over a short period of time can lead to flooding, an increase is disease-carrying mosquitoes, water contamination and mental health issues due to stress. The 2023 Durham Community Health Assessment has a Severe Storms and Precipitation section explaining the impacts of excessive precipitation on public health in Durham.

The NC Climate Science Report defines extreme precipitation events as days on which three inches or more rain, hail, and/or snow falls over an area. Rainfall can also cause serious problems if a lot of it falls in a short amount of time, or a lighter amount falls over a long time. For example, flash floods can be dangerous even though the duration of the rainstorm is relatively short. At other times, rain can fall continuously over an area for a long time period. Both can accumulate water at the surface at a rate higher than the amount of water that the ground can absorb.

Durham County is experiencing extreme precipitation events more frequently than historical averages and that trend is projected to increase in the next 30 to 80 years.

 Source:  2023 Durham Community Health Assessment - Chapter 11

Some ways of reducing the impacts of excessive precipitation include planting trees, preserving natural areas around streams and rivers, and increasing vegetation in areas that do not currently have a lot of plants and trees.