Ontario County, NY flood risk explained
Flood hazard in Ontario County sits at the 78.8th 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 1.4 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Ontario County's flood-insurance compliance gap
FEMA hasn't published a residential structure count for Ontario County's mapped flood zone, so a reliable mandatory-compliance percentage can't be computed here — see the data quality guide for why this gap exists for roughly a quarter of US counties. Looking beyond the mandated zone, 0.7% of all residential structures in Ontario County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Ontario County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Ontario County ranks 696 — 1 being the highest hazard nationally — and 566 by population among all 3144 counties covered here, where 1 is the largest. Ontario County, New York covers 644.025 square miles and counts roughly 113,012 residents.
Your street may differ from Ontario County's average
Across all of Ontario County's 42,316 residential structures, 297 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Ontario County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. Ontario County's compliance figure is one of the ones affected by FEMA's incomplete denominator data — the data quality guide explains what that means and how many counties it touches.