The disaster databases, explained
Five federal datasets, what each counts, and where they disagree
A county's disaster record comes from five federal databases that count different things: FEMA's declarations count federal decisions (5,269 since 1953), FEMA's flood insurance claims count paid losses (2,663,556), FEMA's National Risk Index models future loss, NOAA's Storm Events Database counts the storms themselves (2,052,037 records since 1950, marine zones included) and the Storm Prediction Center counts tornadoes (73,458). 61% of FEMA's major disaster declarations involve flooding.
By PlainHazard Editorial · Updated · How this was measured
The five databases side by side
| Database | Publisher | One row is | From | Newest |
|---|---|---|---|---|
| Disaster Declarations Summaries (v2) | FEMA (OpenFEMA) | a declaration naming one area (70,407 rows) | 1953 | October 2, 2026 |
| NFIP Redacted Claims (v3) | FEMA (OpenFEMA) | a flood insurance claim | 1978 | as of September 8, 2026 |
| National Risk Index | FEMA | a county's modeled risk (3,232 counties) | model | December 2025 release |
| Storm Events Database | NOAA NCEI | a storm event in a county, forecast zone or marine zone | 1950 | June 30, 2026 |
| Tornado database | NOAA Storm Prediction Center | a tornado, start to end | 1950 | 2025 |
FEMA disaster declarations
FEMA publishes every federal declaration since 1953 through OpenFEMA. There are three kinds: major disaster declarations (2,938, from 1953), emergency declarations (654, from 1974) and fire management assistance declarations (1,677, from 1970). Each row names one designated area, usually a county, so one disaster appears on many rows.
How many declared disasters involve floods? Of the 2,938 major disaster declarations, 1,796 (61%) either carry the incident type Flood or name flooding in their title, such as "Severe Storms and Flooding". Counting incident type Flood alone gives a smaller share, because FEMA files most storm-and-flood disasters under Severe Storm.
Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), through 2026-10-02. OpenFEMA dataset page.
NFIP flood insurance claims
The National Flood Insurance Program's redacted claims file lists 2,663,556 claims since 1978 that PlainHazard maps to a county, with $89.4B paid. It shows where insured flood losses happened; it leaves out uninsured losses, so places with few policies show few claims whatever their floods.
Source: OpenFEMA NfipClaims v3, as of 2026-09-08.
FEMA National Risk Index
The National Risk Index estimates each county's expected annual loss from 18 hazards and combines it with social vulnerability and community resilience into one score. It is a model of the future, not a count of the past. How to read its scores.
Source: FEMA National Risk Index, December 2025 release. FEMA's National Risk Index map.
NOAA Storm Events Database
The National Weather Service files every significant storm in the Storm Events Database, which NCEI publishes about 75 days after each month ends. Coverage grew in steps: tornadoes only from 1950, thunderstorm wind and hail from 1955, all 48 event types from 1996. Many records are filed against a forecast zone rather than a county; PlainHazard places each on the counties its zone covered in that year, and 5,449 land records of 1,999,928 could not be placed.
Source: NOAA NCEI Storm Events Database, file revision 20260918. Search the record at NCEI.
Where they disagree
A county can have many storm records and few declarations, or the reverse: across counties the two barely move together (measured here). A declaration needs a request and a federal decision; a storm record needs a storm and an observer. Neither is wrong; they answer different questions, which is why every PlainHazard county page shows both.
How this was measured
Every count on this page is measured on the files as PlainHazard loaded them, on the dates shown. A declaration is counted once per disaster number, however many states or counties it names.
Sources
FEMA OpenFEMA Disaster Declarations Summaries (v2), through 2026-10-02; OpenFEMA NfipClaims v3 (as of 2026-09-08); FEMA National Risk Index (December 2025); NOAA NCEI Storm Events Database (file revision 20260918); NOAA Storm Prediction Center tornado database.