How much flood risk does Suffolk County actually carry?
Suffolk County lands at the 94.7th percentile of FEMA's National Risk Index for flooding, "Relatively High" territory — well above the national norm for flood hazard — with the hazard split between inland river flooding (about 1.7 times a year) and coastal storm surge (about 7.4 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.
Suffolk County's flood-insurance compliance gap
53.3% of the homes FEMA requires to carry flood insurance in Suffolk County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 2,667 policies against 5,006 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in Suffolk County, not just the ones FEMA mandates, 2.5% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Suffolk County against the rest of the country
Suffolk County sits at rank 180 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 84 of 3144 by population (1 is biggest). Suffolk County, Massachusetts is home to about 793,144 people across 58.257 square miles of land.
Your street may differ from Suffolk County's average
FEMA counts 132,056 residential structures in Suffolk County overall, 3,270 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 Suffolk County's numbers. Because storm surge plays a real role here, the guide to coastal vs. inland flood hazard is worth reading alongside this page.