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How we use the data

Everything on Hazard Compass comes from three public sources published by the Federal Emergency Management Agency (FEMA). We do not create our own risk scores.

1. FEMA National Risk Index

The National Risk Index rates every US county for 18 natural hazards: avalanche, coastal flooding, cold wave, drought, earthquake, hail, heat wave, hurricane, ice storm, inland flooding, landslide, lightning, strong wind, tornado, tsunami, volcanic activity, wildfire and winter weather. We use the December 2025 version.

  • Ratings run from Very Low to Very High. They compare each county with every other county in the country.
  • Scores are percentiles from 0 to 100. A score of 90 means the county's risk is higher than about 90% of US counties.
  • Expected annual loss is FEMA's long-run estimate of the average yearly damage to buildings, people and farm output, in dollars. It is an average over many years, not a forecast for next year.
  • Overall risk combines expected losses with social vulnerability and community resilience.

2. OpenFEMA disaster declarations

We use the Disaster Declarations Summaries dataset, which lists every federal major disaster, emergency and fire management declaration since 1953 and the counties each one covered. We count each declaration once per county, and we leave out non-natural events such as chemical spills and the COVID-19 declarations. Statewide declarations that do not name counties are shown separately. The newest declaration included is from October 27, 2026.

Connecticut replaced its counties with planning regions in 2022. For Connecticut we match older declarations to the new regions, so counts there are approximate.

3. National Flood Insurance Program

For flood insurance we use FEMA's NFIP residential penetration rates (the share of homes with a federal flood policy, as of August 2026) and NFIP redacted claims (claims and amounts paid since 1978). Private flood insurance is not included, so the real share of insured homes is a little higher.

What the data cannot tell you

  • County figures describe a whole county. Risk at a single address can be very different. For a property, check the FEMA Flood Map Service Center and ask about the building's history.
  • Past declarations show where federal help was needed, not every damaging event.
  • Nothing on this site is a quote, an insurance recommendation or safety advice.

Corrections

If something looks wrong, contact us. We fix confirmed errors quickly.