San Juan County, WA flood risk explained
Flood hazard in San Juan County sits at the 58.4th national percentile, below the national norm for flood hazard; driven by coastal storm surge rather than inland rivers — FEMA's model puts a surge event here at about 3.6 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.
Mandatory flood insurance compliance in San Juan County
Out of 348 homes FEMA counts inside San Juan County's mapped flood zone, 54 carry the flood policy federal law requires there — 15.5% compliance, short of full coverage. Looking beyond the mandated zone, 0.7% of all residential structures in San Juan County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where San Juan County ranks
Among the 3144 US counties FEMA scores for flood hazard, San Juan County ranks 1368 — 1 being the highest hazard nationally — and 1894 by population among all 3144 counties covered here, where 1 is the largest. San Juan County, Washington is home to about 18,668 people across 173.916 square miles of land.
What to do next if you own or are buying in San Juan County
95 of San Juan County's 12,915 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where San Juan County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. San Juan County's coastal exposure is covered in the coastal vs. inland flood risk guide, including how storm surge risk differs from river flooding.