FEMA flood map notices

Flood map changes in St. Louis County, Missouri

FEMA has published 6 flood hazard notices covering St. Louis County, Missouri since November 2023. The most recent, map revision flood hazard determinations, was published Nov 20, 2025.

Notices for St. Louis County

Nov 20, 2025Map revisionChanges in Flood Hazard DeterminationsAlso covers 25 other counties
Jun 12, 2025Map revisionChanges in Flood Hazard DeterminationsAlso covers 29 other counties
Jan 16, 2025Map revisionChanges in Flood Hazard DeterminationsAlso covers 20 other counties
Dec 6, 2024Map revisionChanges in Flood Hazard DeterminationsAlso covers 14 other counties
Aug 12, 2024Map revisionChanges in Flood Hazard DeterminationsAlso covers 19 other counties
Mar 14, 2024Map revisionChanges in Flood Hazard DeterminationsAlso covers 22 other counties

Also covered by these notices

FEMA often studies whole watersheds, so one notice can span several counties.

What these notices mean

Proposed: FEMA has new draft flood maps. This starts a 90-day window when owners can appeal with technical data. It's the best time to act.
Final: Appeals are resolved. The new maps usually take effect about six months later, when lenders start applying the new zones.
Map revision: A Letter of Map Revision changes one stretch of the map, often after a levee, channel project or new survey.

Notices are organized by county and community, so a notice for your county doesn't mean your property is changing zones. What flood zones mean