Custer County, MT: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Custer County scores at the 38.3th percentile for flood hazard, rated "Relatively Low" — below the national norm for flood hazard. 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 1 years. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Who actually carries the flood insurance FEMA requires
Out of 3,018 homes FEMA counts inside Custer County's mapped flood zone, 670 carry the flood policy federal law requires there — 22.2% compliance, short of full coverage. Looking beyond the mandated zone, 11.7% of all residential structures in Custer County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Custer County against the rest of the country
Among the 3144 US counties FEMA scores for flood hazard, Custer County ranks 2004 — 1 being the highest hazard nationally — and 2283 by population among all 3144 counties covered here, where 1 is the largest. About 11,964 people live in Custer County, Montana, spread over 3,783.309 square miles.
Your street may differ from Custer County's average
Across all of Custer County's 5,878 residential structures, 687 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Custer 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.