Jefferson County, NY Flood Zone & Flood Risk Data
Jefferson County, NY: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Jefferson County scores at the 78th percentile for flood hazard, rated "Relatively Moderate", a middling flood hazard by national standards. 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 a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Jefferson County's flood-insurance compliance gap
FEMA's own figures for Jefferson County report more NFIP policies in the mapped flood zone than FEMA's own count of residential structures there, which produces a compliance rate over 100%, a data problem on FEMA's side, not evidence that everyone here is over-insured. See the data quality guide for how widespread this is. Looking beyond the mandated zone, 0.6% of all residential structures in Jefferson County carry flood coverage voluntarily or otherwise, relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where Jefferson County ranks
Among the 3144 US counties FEMA scores for flood hazard, Jefferson County ranks 721, 1 being the highest hazard nationally, and 565 by population among all 3144 counties covered here, where 1 is the largest. About 113,140 people live in Jefferson County, New York, spread over 1,267.932 square miles.
Checking a specific address in Jefferson County
FEMA counts 45,113 residential structures in Jefferson County overall, 253 of them carrying some form of NFIP coverage, but a lender or insurer cares about one parcel, not that county total.
Where Jefferson County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. Jefferson 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.