How much flood risk does Frederick County actually carry?
Frederick County lands at the 81.6th 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 4.7 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.
Who actually carries the flood insurance FEMA requires
19.3% of the homes FEMA requires to carry flood insurance in Frederick County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 151 policies against 781 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in Frederick 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 Frederick County compares nationally
Frederick County sits at rank 603 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 246 of 3144 by population (1 is biggest). About 299,317 people live in Frederick County, Maryland, spread over 660.623 square miles.
Checking a specific address in Frederick County
FEMA counts 88,569 residential structures in Frederick County overall, 501 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 Frederick 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.