FEMA NRI v1.20 Methodology
The source and deterministic display rules behind RiskByCounty's county pages.
Frozen source
- Dataset
- FEMA NRI v1.20
- Release
- December 2025
- Source rows
- 3,232
RiskByCounty uses the county table from FEMA National Risk Index v1.20. The refresh pipeline verifies the FEMA archive and extracted source files against frozen SHA-256 values before producing the RiskByCounty-only county artifact.
FEMA National Risk Index documentation →Score and rating fields
| RiskByCounty label | FEMA field |
|---|---|
| NRI score (0–100 relative scale) | RISK_SCORE |
| Official FEMA county rating | RISK_RATNG |
RiskByCounty preserves FEMA's score and official county rating. It does not convert the score into a percentage, create new rating bands, or synthesize a FEMA state score or state rating. State means are explicitly labeled arithmetic summaries of available county scores and are not weighted by residents.
Selected hazard display
FEMA's composite covers 18 hazard categories. RiskByCounty displays five selected categories out of those 18; the selection is not described as complete coverage.
- Flood
- Higher of FEMA Coastal Flooding and Inland Flooding NRI scores. Both source values are disclosed on county pages.
- Wildfire
- FEMA Wildfire NRI score.
- Tornado
- FEMA Tornado NRI score.
- Earthquake
- FEMA Earthquake NRI score.
- Hurricane
- FEMA Hurricane NRI score.
Interpretation boundary
The displayed values are county-level, unitless relative planning indices. RiskByCounty reports source fields and deterministic transformations only. Missing FEMA values remain visibly unavailable rather than being estimated.