NOAA Flood Inundation Mapping Tool Expands to Serve 60% of the US

4 September 2025

An example of NOAA’s Flood Inundation Mapping (FIM) services: This is a simulated image of potential flooding over Warfield, Kentucky, along the Tug Fork River in February 2025. The blue represents the forecast extent of inundation and extends away from the river channel to indicate that numerous structures and streets may be affected by flood waters. Local emergency teams used those maps to deploy the National Guard with high-water vehicles to affected neighborhoods, where they evacuated all the residents before water entered their apartments. (Image credit: NOAA)

NOAA’s National Weather Service (NWS) announced that the groundbreaking experimental Flood Inundation Mapping (FIM) tool has expanded significantly to serve 60% of the US population, up from 30% the previous year.

The FIM provides near-real-time, high-resolution, street-level visualizations of flood waters to assist NWS forecasters in issuing flood watches and warnings. FIM services are now available to twice as many NWS weather forecast offices with new coverage for:

Hawaii and the West Coast;
Portions of South-Central Alaska, including the Cook Inlet, Kenai Peninsula, Copper River, and Prince William Sound watersheds;
The Southwest and Great Plains; and
The Great Lakes and the interior Southeast.

“Flooding is the most frequent severe weather-related threat, and our costliest natural disaster,” said David Vallee, Director, Service Innovation and Partnership Division, NOAA’s National Water Center. “Expanding our FIM availability has been a game-changer in providing actionable, real-time information to emergency and water resource managers, and will expand the delivery of impact-based decision support services to our core partners who work to keep Americans safe and informed.”

As is indicated in this US map, Flood Inundation Mapping (FIM) now extends from the Northeast to the Gulf Coast and across much of the Midwest, along the West Coast, and across Hawaii, Puerto Rico, the US Virgin Islands, and portions of south-central Alaska. Map legend shows 10% of the population served by October 2023 (depicted in green); 30% of the population served by October 2024 (depicted in blue); 60% of the population served by September 2025 (depicted in orange); NWS county warning areas in white; and NWS River Forecast Center boundaries in navy blue. (Image credit: NOAA)

FIM helps provide approximate spatial estimates of land area that is covered in water, based on modeled forecast river flows and current conditions, with detailed information on where flooding impacts may occur.

About NOAA’s Flood Inundation Mapping

FIM services launched in 2023 for 10% of the country, serving portions of Louisiana, New York, Pennsylvania, and Texas. In 2024, FIM expanded to cover 30% of the US population, covering areas stretching from the Mid-Atlantic and eastern Great Lakes to the Lower Mississippi Valley and central Gulf Coast region, Washington, and parts of Oregon in the Pacific Northwest region, and Puerto Rico and the US Virgin Islands.

The expanded FIM maps are available on the National Water Prediction Service website and in several geographic information system applications.

There are four unique maps available in near-real time for the Lower 48 and parts of south-central Alaska:

National Water Model-derived hourly inundation analysis of current conditions
National Water Model streamflow prediction based on a five-day inundation forecast
NWS River Forecast Center (RFC) streamflow prediction-based five-day inundation forecast
Static “categorical” FIM (CatFIM) maps for select NWS River Forecast Points within the FIM domain

FIM services will be slightly different for Hawaii, Puerto Rico, and the US Virgin Islands to capture the fast-response floods on these rivers and streams. As the precipitation forecasting models are different for these areas when compared with the continental US, a 48-hour forecast based on National Water Model streamflow predictions will be used to create FIM instead of the five-day flood inundation forecasts from the National Water Model and RFCs.

An aerial photo of a housing complex surrounded by floodwaters along the Tug Fork River in Martin County, Kentucky, Feb. 17, 2025. (Image credit: US Air Force, Senior Master Sgt. Ben Cole)

Looking ahead

In 2026, FIM will be fully deployed in communities nationwide and available for 110,000 river miles near and downstream of NWS RFC forecast point locations. It will also be available for more than 3.6 million river miles covered by National Water Model forecasts.

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