Warming atmosphere driving more frequent flash floods, experts say

Floodplain development continues despite rising risks, experts say

Climate change is driving increasingly common bouts of heavy rain across the United States that cause deadly and damaging flash floods, and the trend will worsen as the crisis continues, experts said.

Over the past month, states including Alaska, Missouri, New Jersey, New York, Ohio, and Pennsylvania have experienced record rainfall, leading to flash flooding. In Texas, where a year ago 25 campers, two counselors, and the director died in a flood at Camp Mystic, flash flood emergency orders were issued Thursday in two counties, including the one where the camp is located. Gov. Greg Abbott said two people had died in the state. “Our No. 1 focus is saving lives,” Abbott said, adding that more than 70 people had been rescued.

In Missouri, a summer camp experienced flash flooding this month, and more than 200 children and staff were evacuated via helicopter. One woman, Faith Gregory, died after her home was swept away.

Heavy precipitation events have become more common because warming oceans and air have increased evaporation, putting more water vapor into the atmosphere, said Jennifer Francis, senior scientist with the Woodwell Climate Research Center. That vapor acts as a greenhouse gas, creating a positive feedback loop, and “a fuel for storms,” she said, because hurricanes feed off it and storms have “more water to work with.”

The National Oceanic and Atmospheric Administration said heavy rainfall is more likely to cause flash flooding in hilly areas where the soil does not absorb much water, in densely populated areas with impermeable surfaces, and in canyons where hikers can be trapped by rapidly rising water.

Despite scientists’ forecasts and tragedies like the Camp Mystic flood, experts said some government officials are not investing enough money or political capital to upgrade infrastructure and restrict where people can build.

“We have basically built for a climate that no longer exists, and retrofitting our infrastructure is a slow and expensive process,” said Alice Hill, a senior fellow for energy and the environment at the Council on Foreign Relations. “Adding to that challenge is the fact that in many places, climate change – the term – is a dirty word, and that can reduce the initiative to make sure that any investments made today can carry the excess rainfall.”

Much of the country is not prepared for the extreme weather, in part because some cities still use pipes that are more than a century old, Hill said. “That system just can’t carry this kind of rainfall.”

Cities such as Houston and New York have continued to allow developers to build in floodplains, experts said. In central Texas, much of the landscape is hilly, leaving limited space for construction, said Jim Blackburn, an environmental law professor at Rice University. “So that flat land next to the [Guadalupe River] has always been, from a Texas viewpoint, prime for development,” he said.

To protect against property damage and deaths, governments must restrict building in floodplains, Blackburn said. But in Texas and other states, people “generally resist flooding regulations and try to find our way around them as best we can,” he said.

At Camp Mystic, the owners had successfully appealed to the Federal Emergency Management Agency to have some of its buildings removed from a 100-year flood map, which allowed the camp to operate and expand in the potentially dangerous area. In Harris County, Texas, where Hurricane Harvey caused more than $125 billion in damage in 2017, homeowners and developers have appealed to FEMA to have more than 6,500 homes removed from the floodplain map, the Houston Chronicle reported, allowing them to avoid stricter building rules and flood insurance costs. FEMA is now drafting a new flood zone map to adjust for increased rainfall rates.

“People use these maps for decisions on buying real estate. They use these maps to determine the vulnerability of hazardous waste facilities, various types of sensitive private-sector and government facilities, and hospitals,” Blackburn said. Real estate developers are concerned about the potential new map, he said, because it could create liability issues and make properties in the new floodplain less attractive to buyers. “They may have promoted it as not being in the floodplain, and they will have to go out and change all those statements,” Blackburn said.

The Trump administration announced in April 2025 that it was eliminating the Building Resilient Infrastructure and Communities program, which had been slated to provide $882 million in grants for disaster-preparedness projects. A federal judge ordered FEMA to restore the funding in December. A link to the April 2025 press release that announced the end of the “wasteful, politicized grant program” now directs to the FEMA homepage, which promotes $600 million in grants to help communities reduce flood risk.

Efforts to adapt have also encountered political obstacles. The Republican Party of Texas stated in its 2024 platform that it opposes “environmentalism, or ‘climate change’ initiatives, that obstruct legitimate business interests and private property use.”

US cities have invested in the “sponge city” concept, which uses parks, permeable surfaces, and better water-flow systems to absorb and hold excess rainfall, Hill said. But changing the country to adapt to the additional rainfall will take years, she said. In the meantime, officials are trying to keep people safe amid the summer’s heavy rains.