The National Flood Hazard Layer (NFHL) is a geospatial database that contains current effective flood hazard data. FEMA provides the flood hazard data to support the National Flood Insurance Program. You can use the information to better understand your level of flood risk and type of flooding. The simplest way for you to access the flood hazard data, including the NFHL, is through FEMAs Map Service Center (MSC).
If you want to explore the current digital effective flood hazard data in a map, the best tool to use is the NFHL Viewer. From the NFHL Viewer, you may view, download, and print flood maps for your location.
The NFHL is made from effective flood maps and Letters of Map Change (LOMC) delivered to communities. NFHL digital data covers over 90 percent of the U.S. population. New and revised data is being added continuously. If you need information for areas not covered by the NFHL data, there may be other FEMA Flood Hazard Products and Services which provide coverage for those areas.
A list of the types of data available in the NFHL and information about other ways to access the NFHL may be found in the NFHL GIS Services User Guide.
If you need more information about individual tables in the NFHL, the FIRM Database Technical Reference, found at FEMA’s Technical References, includes those details.
For step-by-step instructions on how to read a flood map, you may view the How to Read a Flood Insurance Rate Map Tutorial.
Accessing the NFHL
In the NFHL Viewer, you can use the address search or map navigation to locate an area of interest and the NFHL Print Tool to download and print a full Flood Insurance Rate Map (FIRM) or FIRMette (a smaller, printable version of a FIRM) where modernized data exists. Technical GIS users can also utilize a series of dedicated GIS web services that allow the NFHL database to be incorporated into websites and GIS applications. For more information on available services, go to the NFHL GIS Services User Guide.
You can also use the address search on the FEMA Flood Map Service Center (MSC) to view the NFHL data or download a FIRMette. Using the “Search All Products” on the MSC, you can download the NFHL data for a County or State in a GIS file format. This data can be used in most GIS applications to perform spatial analyses and for integration into custom maps and reports. To do so, you will need GIS or mapping software that can read data in shapefile format.
FEMA also offers a download of a KMZ (keyhole markup file zipped) file, which overlays the data in Google Earth™. For more information on using the data in Google Earth™, please see Using the National Flood Hazard Layer Web Map Service (WMS) in Google Earth™
Using the NFHL to Make Official Determinations
The NFHL Database and GIS Services can be used in maps or application that combine the NFHL flood hazard data with basemaps and other reference data from other sources. However, to use the NFHL data for official purposes, you are responsible for making sure base map data meet FEMA’s accuracy standards and the locations depicted are interpreted properly. The NFHL Viewer provides a default base map that meets the minimum standards.
For the specifics of FEMA’s policy on the use of digital flood hazard data for NFIP purposes, see standards 147, 148, 149, 605, and 606 in the FEMA Policy Standards for Flood Risk Analysis and Mapping.
Links Related to the NFHL
NFHL Status: provides the current status of NFHL database services and data. The announcements section provides information about maintenance windows and new information. The NFHL Inventory Table provides the user with an updated list of data in the NFHL, sortable by state, county, date updated and ID.
GIS Web Services for the FEMA Flood Hazard Data: contains information regarding the various GIS Services available to access the NFHL. This information includes services geared towards experienced GIS users.
Using the National Flood Hazard Layer Web Map Service (WMS) in Google Earth™: shows users how to use the NFHL in the Google Earth ™ application, including information on how to download Google Earth ™ onto your computer and how to download the NFHL or Stay Dry KMZ files.
NFHL Fact Sheets
- National Flood Hazard Layer (NFHL): New Products and Services for FEMA's Flood Hazard Map Data
- Letter of Map Amendment (LOMA) Revalidation Statuses Fact Sheet
- Stay Dry: View Basic FEMA Flood Hazard Information Using Google Earth™
- FEMA NFHL: View Custom Combinations of FEMA Flood Hazard Information Using Google Earth™
- NFHL GIS Data: Perform Spatial Analyses and Make Custom Maps and Reports
- Letter of Map Amendent (LOMA) Revalidation Statuses