Grafton County, NH flood risk explained
Flood hazard in Grafton County sits at the 90.1th national percentile, a middling flood hazard by national standards; driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 4.3 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Who actually carries the flood insurance FEMA requires
Homes with a federally backed mortgage inside Grafton 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, 18% of them do — 225 active policies against 1,250 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 1.1% of all residential structures in Grafton County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Grafton County against the rest of the country
Among the 3144 US counties FEMA scores for flood hazard, Grafton County ranks 330 — 1 being the highest hazard nationally — and 657 by population among all 3144 counties covered here, where 1 is the largest. Grafton County, New Hampshire covers 1,708.61 square miles and counts roughly 93,045 residents.
What to do next if you own or are buying in Grafton County
330 of Grafton County's 29,759 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where Grafton County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. If you're unsure why any of this insurance requirement exists at all, the SFHA explainer covers it from first principles.