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View Your Community’s Preliminary Flood Hazard Data

This page discusses preliminary flood hazard data (preliminary data), including how to use and access the data. This data provides the public an early look at a home or community’s projected risk to flood hazards. This page is geared towards homeowners, community officials, financial lenders and other industry professionals who want to understand how their current effective Flood Insurance Rate Map (FIRM) may change when the preliminary data becomes effective.

Go here to access your preliminary flood data search tool. If the preliminary data search tool is unavailable, please visit the alternate site to view your data.

What is Included in Preliminary Data?

Preliminary data is presented as the best information available at this time and include new or revised Flood Insurance Rate Maps (FIRMs), Flood Insurance Study (FIS) reports and FIRM Databases:Logo for Preliminary flood hazard data

  • A FIRM (also referred to as a flood map) is the official map that shows Special Flood Hazard Areas (SFHA) and the risk premium zones applicable to a community. Risk zones indicated on a FIRM provide a basis for establishing flood insurance coverage premium rates offered through the National Flood Insurance Program (NFIP).
  • FIS reports provide background information on the analysis performed and more precise data on the flood elevations in a community.
  • A FIRM Database is a collection of the digital data that are used in Geographic Information Systems (GIS) applications for creating new FIRMs. These datasets cover a county or a community.

To find your property's effective FIRM, FIS Report and FIRM Database, visit the FEMA Flood Map Service Center (MSC).

In addition to preliminary data, Letter of Map Revision (LOMRs) in the public appeals period will also be made available for view on the MSC, located under the community’s effective FIRM. Prior to a LOMR becoming effective, stakeholders are provided a 90-day appeal period in which they can appeal information contained within the LOMR.

Accessing the Preliminary National Flood Hazard Data

The Preliminary National Flood Hazard Layer is a geospatial database that contains current preliminary flood hazard data. The information can be used to better understand proposed flood hazards in your community.

The Flood Map Changes Viewer (FMCV) is the best way to view the Preliminary National Flood Hazard Layer and Preliminary Changes Since Last FIRM (CSLF) data in a map. The Preliminary CSLF view provides a visual of proposed changes to flood extents or proposed changes to zone designations for a location. The FMCV features the Preliminary Map Comparison Tool through which you may print a report featuring a side by side comparison of effective data and preliminary data a selected location. A tutorial is available to provide additional information on how to use the Preliminary Map Comparison Tool.

Instructions for Using the FMCV:

  • Visit
  • Read the welcome message and press “OK” to continue to the FMCV
  • Type into the address search bar on the top right corner of the page either the exact address, the zip code, or the city and state of the location for which you want to view flood map data
  • Select the magnifying glass symbol to the right of the address search bar or press enter on the keyboard to execute the search and navigate to the location
  • The symbol directly to the left of the address search bar with three pieces of paper is the Layer List symbol, which opens a list of the operational layers that are viewable in the FMCV. Users may select or de-select boxes next to the layers to have the data appear or disappear from the FMCV.
  • The symbol directly to the left of the Layer List symbol is the Legend symbol with a triangle, square, and circle bulleted list. Pressing the Legend Symbol will open a legend defining the various symbols and colors displayed in the FMCV.
  • The plus and minus symbols on the bottom left corner of the FMCV allow users to zoom in or out from the map location.

You may also access the Preliminary National Flood Hazard Layer through FEMA’s Map Service Center Search All Products feature. To view preliminary flood hazard data issued prior to 2013, please contact the FEMA Map Information eXchange (FMIX) at 1-877-336-2627 or

Where Can I Access Preliminary Data?

The public may access their community’s preliminary data by visiting the Preliminary Data Search Tool or through the MSC through the Search All Products or Product Availability Table.

The preliminary data webpages listed above undergo periodic maintenance. If you are unable to access your community’s preliminary data through these channels, please visit this alternate site.

To explore the current digital preliminary flood hazard data in a map, the best tool to use is the Flood Map Changes Viewer. From the Flood Map Changes Viewer, you may view, download, and print flood maps for your location.

What are the Benefits of Preliminary Data?

The release of preliminary data is an important step in a community’s flood mapping lifecycle. There are several benefits for the public and professionals in viewing their community’s preliminary data before it becomes an effective FIRM:

  • Allows the public to voice their opinions or concerns regarding how the data may affect them or to question data accuracy
  • Insurance agents can compare existing FIRMs with preliminary FIRMs to see how their clients may be affected. However, policies cannot be written using preliminary data
  • Loan and mortgage brokers can use preliminary data as a guide to determine whether a property may be mapped into a high-risk area, allowing the borrower to be informed of any changes or requirements before finalizing the loan
  • Real estate agents and brokers can determine what changes are likely to occur and how it might affect any properties for sale
  • Engineers, developers and builders can plan for safer construction

Who Can View Preliminary Data?

Anyone can view their property or community’s preliminary data. These individuals may include:

  • General public
  • Home, property and business owners
  • Community officials
  • Engineers and surveyors
  • Insurance and real estate agents
  • Community developers and planners
  • Floodplain and emergency managers
  • Financial bankers and lenders

What Is The Difference Between Preliminary and Effective Data?

Preliminary data are not for use, distribution or replication until the data are finalized and labeled as “effective” on the MSC. Preliminary data are for review and guidance purposes only. By viewing preliminary data, the user acknowledges that the information provided is preliminary and subject to change. Preliminary data, including new or revised FIRMs, FIS reports and FIRM Databases, are not final and are presented on the MSC as the best information available at this time. Additionally, preliminary data cannot be used to rate flood insurance policies or enforce the federal mandatory purchase requirement. Preliminary data will be removed and replaced once effective data are available.

Unlike preliminary data, effective data and maps are official and should be used for National Flood Insurance Program (NFIP) purposes and viewing risk premium zones applicable to a community. If you don’t want to view preliminary data, go to your community’s effective FIRM or effective FIS Report available on the MSC.

Accessing the Pending National Flood Hazard Layer

The Pending National Flood Hazard Layer is a geospatial database comprised of final, post-preliminary flood maps that have been assigned a Letter of Final Determination and delivered to communities for awareness five to six months prior to becoming effective. The Pending National Flood Hazard Layer is for awareness of upcoming changes to regulatory flood map information. Until the data becomes effective and it appears in the NFHL, the data should not be used to rate flood insurance policies or enforce the federal mandatory purchase requirement.

The Flood Map Changes Viewer (FMCV) includes the Pending National Flood Hazard Layer, the Preliminary National Flood Hazard Layer, and Preliminary Changes Since Last FIRM (CSLF) data in an interactive mapping application. If you need information for areas not covered by the Pending National Flood Hazard Layer, there may be other FEMA Flood Hazard Products and Tools that cover those areas.

Are All Preliminary Data Available?

Preliminary data was phased into this new search tool beginning in May 2013. To view preliminary data issued before May 2013 or if you have questions about where to find your community’s preliminary data, contact the FEMA Map Information eXchange (FMIX) at 1-877-336-2627 or e-mail

Last Updated: 
10/02/2019 - 10:34