NOAA Expands Flood Mapping to Nearly All Americans
NOAA's National Weather Service has expanded experimental Flood Inundation Mapping to cover nearly 100% of the U.S. Population, a major increase from 60%.
NOAA's National Weather Service has expanded its Flood Inundation Mapping tool to nearly 100% of the U.S. Population on an experimental basis. This Flood Inundation Mapping expansion by NOAA in 5 marks a dramatic increase from the previous coverage of just 60% of the population.
How FIM works to predict and visualize flood risk
FIM is a tool for predicting river flooding. It uses model forecast river flows and current conditions to estimate the land area that will be covered in water in the coming days. The system alerts forecasters, emergency managers, and the public to the latest river and stream flooding conditions. It predicts where flooding impacts may occur.
Real-world use in evacuations and emergency response
The tool has proven critical in recent emergencies. In spring 2025, the NWS office in Nashville, Tennessee, used FIM to provide information that helped a senior assisted living facility in Macon County evacuate residents hours before floodwaters arrived. That same April, the NWS office in Little Rock, Arkansas, shared FIM with the city of Hardy, which conducted door-to-door evacuations with a nearly 100% success rate.
During the July 4-7 weekend in 2025, the NWS Austin/San Antonio office distributed FIM to emergency managers in Georgetown, Texas, enabling road closures and evacuations as storms developed. Earlier, in January 2025, the NWS office in Shreveport, Louisiana, used FIM to warn of a large rise on Oklahoma's Glover River, allowing local personnel to evacuate residents preemptively. In April 2026, the NWS Grand Rapids office relied on FIM during major flooding on Michigan's Muskegon River where other guidance was scarce. Ken Graham, National Weather Service Director, said: "FIM has been a game changer when briefing emergency managers, first responders, and communities facing flood risk."
Expanded coverage and public access to FIM data
The expanded system now depicts flooding potential along 3.3 million river miles across the continental U.S., U.S. Territories, and Hawaii. Recent additions include coverage for the southeastern U.S. Coast, Florida, the Great Lakes region, New England, the Rocky Mountains, the Dakotas, and western Nebraska. Neil Jacobs, Ph.D., NOAA Administrator, noted the tool's importance, stating: "Inundation maps are a critical tool for assessing the impacts of flooding."
Multiple versions of FIM data are publicly accessible. For the Lower 48 states and parts of south-central Alaska, four near-real-time products are available. Hawaii, Puerto Rico, and the U.S. Virgin Islands have a slightly different suite. The maps are available on the National Water Prediction Service website and in various GIS applications in multiple file types.
| Region | Available FIM Services |
|---|---|
| Lower 48 & parts of Alaska | National Water Model hourly analysis, National Water Model five-day forecast, NWS River Forecast Center five-day forecast, Static CatFIM for select forecast points |
| Hawaii, Puerto Rico, U.S. Virgin Islands | National Water Model hourly analysis, National Water Model 48-hour forecast, Static CatFIM for select gauged locations |
Limitations and ongoing gaps in FIM coverage
Despite the broad expansion, gaps remain. The tool does not yet cover northern and western portions of Alaska, Guam, the Northern Mariana Islands, or American Samoa. NOAA’s Office of Water Prediction, which coordinates these activities, continues its work. Expanded FIM maps are publicly available on the National Water Prediction Service website and in several GIS applications in multiple file types.
