Is Napa County, CA in a flood zone?
FEMA's National Risk Index puts Napa County's flood hazard at the 95.8th percentile nationally — well above 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 1.1 times a year. That's a county-wide figure, not a per-address one — FEMA's parcel maps are a live lookup, not a bulk file.
Mandatory flood insurance compliance in Napa County
Out of 1,833 homes FEMA counts inside Napa County's mapped flood zone, 664 carry the flood policy federal law requires there — 36.2% compliance, short of full coverage. Across all residential structures in Napa County, not just the ones FEMA mandates, 1.9% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Where Napa County ranks
Napa County sits at rank 144 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 497 of 3144 by population (1 is biggest). Napa County, California covers 751.976 square miles and counts roughly 132,727 residents.
Your street may differ from Napa County's average
Across all of Napa County's 45,738 residential structures, 868 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Napa 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.