If it seems like you’re hearing about flash flood warnings more than usual, you aren’t wrong. The National Weather Service has issued more flash flood warnings than in any other year since records began in 1986 through July 15th in 2025. More than 3,000 flash flood warnings, with the Appalachians, Ozarks, and Southern Plains hit the hardest.
Through July 15th, the number of flash flood emergencies issued is the second highest on record with 47. From July 1-15 alone, more than 1,200 reports of flooding were recorded, which is 75% above the early-July average.
So what is causing this increase in flooding?
For starters, flash floods are most common in summer months because daytime heating helps fuel thunderstorms. Warmer air can also hold more moisture, giving storms the potential to produce higher rainfall rates. Summer storms also tend to move more slowly due to upper-level winds being weaker in the summer. When storms slow, or even stall, more rain falls over a location, sometimes at a rate that is faster than what the ground can absorb or faster than then infrastructure can drain it.
Of course, climate change is also amplifying the conditions that make flash flooding more likely and more severe. For every degree Celsius, or about 2 degrees Fahrenheit, of warming, the atmosphere can hold about 7% more water vapor, giving storms more fuel for intense rainfall. As overall global temperatures increase, moisture-rich air that was once confined to the warm tropics is reaching areas further north, bringing tropical rainfall to more parts of the world. At the same time, wildfires and droughts are becoming more frequent, leading to more burn scars and flash flood potential.
Ninety percent of U.S. cities have seen increases in hourly rainfall rates since 1970. Many of the nation’s roads and drainage systems were not designed to handle rainfall events of this magnitude. As the world continues to warm and extreme rainfall events become more common, more communities will be at risk.
