Updated May 2026
Flood Risk Tools
Free, public-data tools for exploring flood risk across 3.3K U.S. counties. Every tool is powered by the FEMA OpenFEMA API — the same NFIP claim and federal disaster-declaration datasets used by federal regulators and major insurers — augmented with hydrology context from USGS Water Data and FEMA flood-zone designations from the FEMA flood-mapping program.
What Each Tool Does
The four tools below cover the most common flood-risk questions: which counties are most exposed, where losses concentrate, how a particular state stacks up nationally, and what the score looks like for any specific county. All four share the same underlying data — they differ only in the lens they apply. Score weighting and dataset limitations are documented on the methodology page.
Flood Risk Rankings
See which counties face the highest and lowest flood risk, ranked by composite score, claims volume, payouts, active policies, and disaster declarations.
Six rankings cover the most-asked questions: who has the most NFIP claims, who has absorbed the largest total payouts, who has logged the most federal disaster declarations, who carries the most active policies, plus the riskiest and safest composite-score lists.
View RankingsCompare Counties
Compare the riskiest and safest counties side by side. See how flood risk varies across the country.
The compare view shows the top-10 riskiest and bottom-10 safest counties together with combined claim counts and payouts, making the size of the U.S. flood-risk concentration visible at a glance.
Compare NowState Explorer
Browse flood risk data for any U.S. state. See county-level breakdowns, average risk scores, and total NFIP claims.
Each state page lists every county sorted by score, the grade-distribution histogram, riskiest and safest within the state, and how the state compares with the U.S. average — useful for relocation, real-estate, or insurance research.
Browse StatesCounty Search
Search for any county to see its flood risk score, grade, FEMA claims history, and disaster declarations.
Typeahead search on the homepage spans every county in the dataset. The county profile shows score, grade, claim count, total payouts, disaster count, active NFIP policies, and the four factor scores that produce the composite.
Search CountiesHow to Combine the Tools
The tools work best together. A typical workflow: start at the state explorer to understand the regional picture; drop into a single county profile to see the four factor scores and full claim history; compare with two or three nearby counties to triangulate. For real-estate or relocation decisions, layer in the FEMA flood-zone designation for the specific parcel and check the nearest USGS gauge for recent crest history.
For quick browsing, the riskiest counties, highest payouts, and most claims rankings each take ten seconds to scan and surface non-obvious patterns — for example, states that don't make headlines but quietly sit in the top decile of claim counts.
Data Sources & Refresh Cadence
All inputs are U.S. government public-domain work. The tools refresh whenever the underlying data pipeline re-runs against the OpenFEMA API; FEMA's own publication cadence for NFIP claims is roughly quarterly, so tools here can lag actual events by up to three months. Real-time storm-surge and stream-gauge readings — useful as a complement during active weather — live with NOAA and USGS rather than FEMA.
Frequently Asked Questions
What data powers these tools?
Every tool on this page is built on two FEMA OpenFEMA datasets: DisasterDeclarationsSummaries v2 (federally declared disasters filtered to flood-related types) and FimaNfipClaims (individual NFIP flood-insurance claims aggregated by county FIPS code). The current refresh covers 3.3K counties, 100K claims, and 1.4K federal disaster declarations.
How is the composite flood risk score calculated?
Each county receives a 0–100 score: 40% claims density, 25% disaster frequency, 20% claim severity, 15% year-over-year trend. Letter grades A–F bucket the score for fast comparison. Full math is on the methodology page.
Are these tools free?
Yes. Every tool, every dataset, every page is freely available. The data itself is U.S. government public-domain work; no licensing or registration is required to view, share, or cite the figures presented here.
How often does the data refresh?
The pipeline refreshes from the OpenFEMA API on a recurring schedule. FEMA itself republishes NFIP claims roughly every quarter, so figures here can lag actual events by up to three months. The current data was last updated on 2026-05-16.
Can I cite numbers from these tools in a report or article?
Yes. Cite "FloodRiskData (floodriskdata.org), drawn from FEMA OpenFEMA NFIP claims and disaster declarations." Always link to the underlying FEMA data when accuracy matters; the public flood-mapping portal is at fema.gov/flood-maps and real-time hydrology lives at waterdata.usgs.gov.
Free flood risk tools — rankings, comparisons, state explorer, and county search — built on FEMA NFIP and disaster-declaration data covering 3.3K U.S. counties.