Record 2025 flash floods signal rising climate risk in U.S.

A surge of sudden, deadly floods across the United States this summer stretched emergency systems and illuminated the scientific forces that make today's storms more dangerous, experts said.

The U.S. National Weather Service noted on Saturday that it had issued more than 3,600 flash flood warnings in 2025, a pace that could surpass the typical yearly total of about 4,000, as torrential downpours continued into late July.

Texas has borne the brunt. On July 4, walls of water swept through the Guadalupe River valley, killing at least 135 people statewide. Kerr County lost 107 lives in the tragedy, including dozens of children at a summer camp, according to local officials cited by environmental news outlet Grist. River gauges in nearby Kerrville showed water levels rising more than 11.3 meters in 45 minutes, overwhelming rescuers.

Scientists said warm oceans had pumped record amounts of water vapor into the atmosphere this year, while a weak jet stream had allowed storm clouds to linger over the same areas.

The combination made 2025's thunderstorms unusually intense, Jeffrey Basara, a meteorology professor at the University of Massachusetts Lowell, wrote for The Conversation on Friday. He added that regions east of the Rocky Mountains received at least 50 percent more rain than usual between mid-April and mid-July.

Surface conditions compound the danger, the expert said, adding that saturated soils, steep terrain and sprawling pavement funnel water into creeks and streets at breakneck speed. The July 4 deluge struck the river's headwaters, which Basara called the worst possible setup, sending a torrent racing downstream.

Climate change is also sharpening the edge. The latest science suggested the Texas Hill Country floods were about 7 percent more severe because higher temperatures intensify rainfall, Annalisa Peace, executive director of the Greater Edwards Aquifer Alliance, wrote in the San Antonio Express News on Saturday.

Basara warned the pattern was likely to intensify, citing climate models that showed the heaviest U.S. downpours would continue to grow stronger as temperatures climb, raising the risk of future flash flood disasters.

Meanwhile, millions of U.S. homes are situated in flood-prone zones. Grist reported 7.9 million structures lie inside areas the U.S. Federal Emergency Management Agency labeled as having at least a 1-percent annual chance of flooding.

Experts urged stronger building codes, updated flood maps and green infrastructure.

With oceans warming and development marching into floodplains, scientists warned that the "summer of flash flooding" may be less a fluke than a preview of what lies ahead for the United States and, by extension, a world grappling with a wetter, warmer climate.