How much flood risk does Warren County actually carry?
Warren County lands at the 83.9th percentile of FEMA's National Risk Index for flooding, "Relatively Moderate" territory — a middling flood hazard by national standards — with the hazard driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 3.1 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Warren County's flood-insurance compliance gap
Homes with a federally backed mortgage inside Warren 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, 21.2% of them do — 269 active policies against 1,270 structures FEMA counts in that zone, leaving a real compliance gap. Across all residential structures in Warren County, not just the ones FEMA mandates, 0.6% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
How Warren County compares nationally
Warren County sits at rank 530 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 287 of 3144 by population (1 is biggest). Warren County, Ohio covers 401.415 square miles and counts roughly 256,059 residents.
Your street may differ from Warren County's average
434 of Warren County's 78,463 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Warren 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.