How the composite risk score works
The composite score is a 0–100 scale, where higher means more risk. It's a simple weighted combination of four public data sources — nothing more. No proprietary model, no hidden inputs.
Score bands
The number is grouped into four bands for a plain-language label. These cutoffs are fixed and are the same ones the widget uses to colour the score:
- Minimal — 0–24
- Moderate — 25–49
- High — 50–74
- Critical — 75–100
The score is rescaled against only the inputs that were actually available for an address, so a missing data source doesn't silently pull the number down.
Flood zone
From the FEMA National Flood Hazard Layer. Special Flood Hazard Area (SFHA) zones score highest; Zone X (minimal hazard) scores lowest. Locations with no modernized flood map coverage are excluded from the score rather than assumed low-risk.
Wildfire risk
From the USDA Forest Service's Wildfire Risk to Communities dataset — specifically, the "Risk to Potential Structures" layer, which asks the question this page actually needs answered: what would the wildfire risk be to a home at this location? It factors in nearby wildland fuel out to about a mile, so a home near dense forest is scored differently from one deep in a city even though both may sit on developed land. Locations in the highest 5% of risk nationwide score highest.
One important caveat: risk classes are ranked against all US land nationwide, wildland included — a home with real, meaningful local wildfire exposure can still land in a lower band next to the country's highest-fuel wilderness elsewhere. This is a landscape-level estimate, not a substitute for a site-specific defensible-space assessment, and it doesn't account for a particular home's construction materials or upkeep.
Storm history
From the NOAA NCEI Storm Events Database, county-level, trailing 10 years. Each recorded event contributes points weighted by severity (tornadoes and hurricanes weigh more than thunderstorm wind advisories), capped so a very storm-heavy county doesn't dominate the whole score.
Earthquake risk
From USGS's Seismic Design Maps — the same values used in building-code earthquake design, assuming a typical single-family home and no site-specific soil survey (the standard default assumption when one isn't available). Higher seismic design categories score highest.
What's excluded
If a source is unavailable for a given address (upstream outage, or no coverage at that location), it's excluded from the score entirely — not treated as zero risk — and the API response lists which inputs were actually used.
Radon potential (from the EPA Map of Radon Zones) and levee protection status (from the USACE National Levee Database) are shown in the widget but are not part of this score. They're health/inspection and mitigation-context concerns, not the kind of catastrophe risk the other four inputs measure, so folding them into the same number would blur different questions together. A levee reduces flood risk but does not eliminate it — levees can be overtopped or fail.
A "Neighborhood snapshot" (median household income, population, owner-occupied %, bachelor's-degree-or-higher %, median home value, median gross rent, median year built, and vacancy rate — all from the Census Bureau's American Community Survey) is also shown but excluded from the score for the same reason — it's context about the area, not a catastrophe peril.
This score is an informational estimate built entirely from public government data. It does not replace an official flood determination, a licensed inspection, or an underwriting decision.