Fast Facts About Flash Flooding

Fast Facts About Flash Flooding

They Are Powerful and Dangerous

Flash floods can bring walls of water up to 20’ high. Only six inches of rapidly moving water can sweep a full grown person off their feet and two feet of water can sweep away a car, uproot trees, and level some buildings. According to the National Weather Service, flash floods are the #1 weather-related killer in the United States.

They Are Common

After wildfires, flash floods are the most widespread natural disaster.

They Happen Fast

To be considered a flash flood, flooding must begin within 6 hours of heavy rainfall. However, flash floods often happen within only 3 hours of the original catalyst.

There Are Many Contributors

There are many factors that can cause flash flooding, including rain intensity, rainfall location and distribution, topography and land use, vegetation and growth, soil types, and soil water content.

They Can Occur Anywhere

Communities that are in low-lying areas, near water, without natural drainage, or are downstream from a dam or levee, are the most prone to flash flooding. But, flash floods can happen anywhere – all 50 U.S. states are subject to flash floods, no exceptions.

They Aren’t Just Caused by Rain

Rain may be the cause of most flash floods, but levee or dam failures, mudslides, and jams caused by debris are all capable of causing a flash flood.


To learn more about flash floods, go to

Additional flooding facts may be found at


Select your region from the links below to view local Flood Warning Systems, which include real-time maps.


Harris County:

Bastrop, Blanco, Burnet, Caldwell, Fayette, Hays, Lee, Llano, Travis, and Williamson Counties:

Bexar County:!/main/map


Fort Worth: