FEMA flood map notices

Flood map changes in Sonoma County, California

FEMA has published 6 flood hazard notices covering Sonoma County, California since November 2023. The most recent, map revision flood hazard determinations, was published Aug 21, 2026.

Notices for Sonoma County

Aug 21, 2026Map revisionChanges in Flood Hazard DeterminationsAlso covers 24 other counties
Dec 18, 2025Map revisionChanges in Flood Hazard DeterminationsAlso covers 28 other counties
Dec 8, 2025ProposedProposed Flood Hazard DeterminationsAppeal period closed Mar 9, 2026
Apr 1, 2024FinalFinal Flood Hazard DeterminationsAlso covers 13 other counties
Jan 5, 2024Map revisionChanges in Flood Hazard DeterminationsAlso covers 47 other counties
Nov 9, 2023Map revisionChanges in Flood Hazard DeterminationsAlso covers 58 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