Monday, September 28th, 2026 — NOAA’s National Weather Service has expanded its Flood Inundation Mapping system to nearly nationwide coverage, giving forecasters, emergency managers and the public access to neighborhood-scale estimates of where river and stream flooding could occur.
The experimental system, known as FIM, previously covered about 60% of the country. It now maps flooding potential along approximately 3.3 million river miles across the continental United States, Hawaii and U.S. territories.
FIM combines forecast river flows and current conditions to estimate the land area that could be covered by water. The maps can show potential flooding over the following several days rather than limiting forecasts to expected river crest heights.
For property and catastrophe claims operations, the expanded coverage provides another public data source that can help identify areas facing potential river flooding before losses are reported. Adjusters and claims managers can also use the maps alongside weather forecasts, policy information and field reports when planning staffing, travel and inspections after a flood event.
Newly covered areas include Florida and the southeastern U.S. coast, the Great Lakes region, New England, the Rocky Mountains, the Dakotas and western Nebraska.
NOAA Administrator Neil Jacobs said inundation maps help assess flood impacts and provide more detailed information than river crest forecasts alone. National Weather Service Director Ken Graham said the maps have been used in briefings for emergency managers, first responders and communities facing flood risk.
The National Weather Service introduced FIM in 2023 with coverage reaching about 10% of the U.S. population. Coverage expanded to 60% in 2025 before the latest increase to nearly 100% of residents.
Some gaps remain. The system does not yet cover northern and western portions of Alaska, Guam, the Northern Mariana Islands or American Samoa.
Four near-real-time FIM products are available for the Lower 48 states and portions of south-central Alaska. They include an hourly National Water Model analysis of current conditions, a five-day National Water Model inundation forecast, a five-day River Forecast Center inundation forecast and static categorical maps for selected National Weather Service river forecast points.
Hawaii, Puerto Rico and the U.S. Virgin Islands have access to the hourly National Water Model analysis, a 48-hour inundation forecast and categorical flood inundation maps at selected gauged locations.
The maps are publicly available through the National Water Prediction Service and through GIS applications in multiple file formats. NOAA’s Office of Water Prediction, a division of the National Weather Service, manages the program.
