Is Sierra County, CA in a flood zone?
FEMA's National Risk Index puts Sierra County's flood hazard at the 37.7th percentile nationally — below the national norm for flood hazard — driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about once every 7 years. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Sierra County's flood-insurance compliance gap
Homes with a federally backed mortgage inside Sierra County's mapped high-risk flood zone (the Special Flood Hazard Area, or SFHA) are legally required to carry an NFIP flood policy. In practice, 15.9% of them do — 32 active policies against 201 structures FEMA counts in that zone, leaving a real compliance gap. Across all residential structures in Sierra County, not just the ones FEMA mandates, 1.8% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Where Sierra County ranks
Sierra County sits at rank 2025 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 2952 of 3144 by population (1 is biggest). Sierra County, California is home to about 3,113 people across 953.168 square miles of land.
Your street may differ from Sierra County's average
FEMA counts 2,011 residential structures in Sierra County overall, 37 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Sierra County's numbers. The guide to what the Special Flood Hazard Area actually means explains why the mandatory-insurance rule exists and who it applies to.