FEMA Flood Zones in San Francisco County, California

San Francisco County, California is home to 826,079 residents. Land Owl's FEMA flood zone layer records the following within the county boundary — Land in a FEMA Special Flood Hazard Area: 1,157 acres. Share of mapped land in a Special Flood Hazard Area: 3.9%. Share of the county with a published FEMA flood map: 100%. Largest mapped flood hazard area: Coastal high hazard (V/VE) — 590 acres. Distinct flood hazard categories mapped: 4. Distinct FEMA flood zone codes mapped: 6. Most widespread FEMA flood zone: Zone X — 28,653 acres. Land in the 0.2% annual chance (500-year) floodplain: 451 acres. Every feature shown on the map above is clickable, and the figures on this page are derived from the same data the map renders, so they always agree. A free Land Owl account adds parcel boundaries, ownership records, soils, wetlands and topography over the same view.

Frequently asked questions

How much of San Francisco County, California is in a FEMA flood zone?

Land Owl maps 1,157 acres of San Francisco County, California inside a Special Flood Hazard Area, which is 3.9% of the land FEMA has flood-mapped in the county. That is a regulatory designation used for floodplain management and federal flood-insurance requirements — it is not a prediction that the land will flood.

Is this flood zone map free to use?

Yes. This map is free to view. A free Land Owl account unlocks the other data layers, parcel boundaries and ownership records.

Where does this data come from?

Land Owl maps flood zones from FEMA's National Flood Hazard Layer (NFHL), the digital record of the effective Flood Insurance Rate Maps. It is a screening view, not a flood determination: FEMA revises maps, 495 US counties have never had a digital FIRM published at all, and a lender or insurer will ask for the official record. Check the FEMA Map Service Center, or ask your local floodplain administrator, before you rely on a zone.

Is land outside the flood zone safe from flooding?

No. A Special Flood Hazard Area marks where FEMA has studied and mapped a 1% annual chance of flooding; ground outside one has a lower mapped risk, not no risk, and some of it has never been studied at all. Roughly a quarter of US flood-insurance claims come from outside high-risk zones.

What is the difference between a 100-year and a 500-year flood zone?

They are shorthand for annual probability, not for how often a flood happens. A 100-year flood zone has a 1% chance of flooding in any given year; a 500-year zone has a 0.2% chance. Either can flood twice in a decade — the odds reset every year.