Martin County, FL: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Martin County scores at the 83.3th percentile for flood hazard, rated "Relatively Moderate" — a middling flood hazard by national standards. The hazard here is driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about once every 2 years. That's a county-wide figure, not a per-address one — FEMA's parcel maps are a live lookup, not a bulk file.
Who actually carries the flood insurance FEMA requires
Homes with a federally backed mortgage inside Martin 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, 77.8% of them do — 3,037 active policies against 3,905 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 14.1% of all residential structures in Martin County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where Martin County ranks
Among the 3144 US counties FEMA scores for flood hazard, Martin County ranks 549 — 1 being the highest hazard nationally — and 423 by population among all 3144 counties covered here, where 1 is the largest. Martin County, Florida covers 543.873 square miles and counts roughly 165,666 residents.
Your street may differ from Martin County's average
9,539 of Martin County's 67,665 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where Martin 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.