How much flood risk does Lyon County actually carry?
Lyon County lands at the 19.6th percentile of FEMA's National Risk Index for flooding, "Very Low" territory — among the lowest flood hazard in the country — with the hazard driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 2.4 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
Lyon County is one of the counties where FEMA's own denominator for mandated flood-zone structures is missing, so no compliance rate is shown rather than a guessed one — the data quality guide covers how common this is. Across all residential structures in Lyon County, not just the ones FEMA mandates, 0.7% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Lyon County against the rest of the country
Lyon County sits at rank 2569 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 2263 of 3144 by population (1 is biggest). Lyon County, Iowa covers 587.609 square miles and counts roughly 12,378 residents.
Your street may differ from Lyon County's average
FEMA counts 5,408 residential structures in Lyon County overall, 39 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 Lyon County's numbers. See the data quality guide for why Lyon County, like hundreds of other counties, doesn't get a clean compliance percentage.