The Texas floods in July 2025 were caused by a combination of extreme meteorological, geographic, and hydrological factors. A "worst case scenario" of weather conditions occurred with exceptionally heavy and persistent rainfall over central Texas, fueled by moist air from the Gulf of Mexico, remnants of Tropical Storm Barry, and tropical moisture from the eastern Pacific. This created slow-moving thunderstorms that dumped as much as 18 inches of rain in some areas in just a few hours, overwhelming the terrain.
The Texas Hill Country region's steep, hilly landscape with mostly shallow, rocky soils, and flashy karst geology caused rapid runoff into rivers rather than absorption, leading to swift flood rises. The Guadalupe River notably rose 26 feet in 45 minutes, bursting its banks and causing sudden, devastating flash floods.
High soil moisture prior to the event meant the ground was nearly saturated, which limited absorption and increased runoff. The combination of intense rainfall, saturated soils, and the landscape's characteristics made the flooding extremely severe and deadly, especially in populated river valleys and narrow canyons.
In summary, the Texas floods were due to an extraordinary volume of rain from stalled storms fueled by tropical moisture, combined with the physiographic features of the region that promoted rapid runoff, leading to catastrophic flash flooding.
