Flooding
Whenever rainfall or snowmelt accumulates faster than soils can absorb it or rivers can carry it away, flooding can occur.
Nearly every location in the United States has some flood risk. Intense rainfall, multi-day rainstorms, and rapid melting of snowpack can result in flooding.
The warmer our atmosphere gets, the more moisture it can hold, so climate change has increased the intensity and frequency of extreme precipitation, one factor in flooding. Extreme precipitation events can be especially problematic in urban areas where rain runs off roofs and along paved surfaces with no opportunity to soak into the ground. Runoff from heavy rains and/or melting snow also has the potential to overwhelm infrastructure such as culverts, bridges, and stormwater systems.
The United States Geological Survey's National Water Dashboard provides access to data from more than 13,000 stations that monitor streams and other conditions related to water. Additionally, the National Oceanic and Atmospheric Administration's National Weather Service, in collaboration with other federal agencies and state, Tribal, and local emergency managers, operates 13 River Forecast Centers across the country. Each center monitors river levels, snowpack, and other conditions related to water. The centers prepare river level forecasts and issue official flood alerts as necessary.
Maps
The U.S. federal government has extensive data resources that can be used at national, regional, and local levels to monitor flooding conditions and explore trends. Here's a sampling of maps and data visualizations related to flooding.
Current status
This map shows predictions for total precipitation over the next 72 hours. It also highlights areas currently under a National Weather Service Flood Watch or Flood Warning.
Search for or zoom to a location of interest and click or tap the map to explore details.
Each month, NOAA's Climate Prediction Center produces an outlook showing forecaster's confidence in predictions for above, below, or near normal precipitation over the next month and the next season. Change the map to show or precipitation outlooks.
Click any shaded area on either map for an explanation of the outlooks.
Flood hazard areas
Shading on this map shows areas where flood hazards exist, according to the Federal Emergency Management Agency (FEMA) . Areas with no shading have not been mapped.
Click or tap any shaded area for details.
Future projections: days with extreme precipitation
Extreme precipitation events are those in the top 1% of all historic daily totals.
This map shows projections for the annual number of days with extreme precipitation around 2050, if emissions of heat-trapping gases continue increasing.
Change the map to see where and by how much the annual number of days with precipitation over 1 inch are projected to increase or decrease around 2050.
Click or tap the map for details.
Resources to explore
Here's a selection of federal resources related to flooding.