How much flood risk does Snohomish County actually carry?
Snohomish County lands at the 95.7th percentile of FEMA's National Risk Index for flooding, "Relatively High" territory — well above the national norm for flood hazard — with the hazard driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about once every 3 years. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Who actually carries the flood insurance FEMA requires
27.3% of the homes FEMA requires to carry flood insurance in Snohomish County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 1,391 policies against 5,101 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in Snohomish County, not just the ones FEMA mandates, 0.7% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Snohomish County against the rest of the country
Snohomish County sits at rank 147 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 72 of 3144 by population (1 is biggest). Snohomish County, Washington covers 2,086.518 square miles and counts roughly 864,113 residents.
What to do next if you own or are buying in Snohomish County
FEMA counts 263,689 residential structures in Snohomish County overall, 1,769 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 Snohomish 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.