In what experts call "Flash Flood Alley," the terrain reacts quickly to rainfall steep slopes, rocky ground, and narrow riverbeds leave little time for warning.

While local and state officials in Texas have said they were caught off guard by the severity of the flooding, the region is prone to extreme flooding, Marshall Shepherd, director of the Atmospheric Sciences Program at the University of Georgia and former president of the American Meteorological Society, told ABC News.

The record of frequent, often deadly floods in Central Texas goes back more than 200 years to July 1819, when floodwaters spilled into the major plazas of San Antonio. That city on the edge of the Hill Country was hit by major floods again in 1913, 1921, 1998 and 2025, to cite a few examples.