Deadly and destructive flash flooding in Texas and several other states in July 2025 is raising questions about the nation’s flood maps and their ability to ensure that communities and homeowners can prepare for rising risks.
The same region of Texas Hill Country where a flash flood on July 4 killed at least 129 people was hit again with downpours a week later, forcing searchers to temporarily pause their efforts to find missing victims. Other states including New Mexico, Oklahoma, Vermont and Iowa also saw flash flood damage in July.
The U.S. Federal Emergency Management Agency’s flood maps are intended to be the nation’s primary tool for identifying flood risks. Originally developed in the 1970s to support the National Flood Insurance Program, these maps, known as Flood Insurance Rate Maps, or FIRMs, are used to determine where flood insurance is required for federally backed mortgages, to inform local building codes and land-use decisions, and to guide flood plain management strategies.
In theory, the maps enable homeowners, businesses and local officials to understand their flood risk and take appropriate steps to prepare and mitigate potential losses.
But while FEMA has improved the accuracy and accessibility of the maps over time with better data, digital tools and community input, the maps still don’t capture everything – including the changing climate. There are areas of the country that flood, some regularly, that don’t show up on the maps as at risk.
I study flood-risk mapping as a university-based researcher and at First Street, an organization created to quantify and communicate climate risk. In a 2023 assessment using newly modeled flood zones with climate-adjusted precipitation records, we found that more than twice as many properties across the country were at risk of a 100-year flood than the FEMA maps identified.
Even in places where the FEMA maps identified a flood risk, we found that the federal mapping process, its overreliance on historical data, and political influence over the updating of maps can lead to maps that don’t fully represent an area’s risk.
