Big Horn County, Wyoming

What hazards hit Big Horn County most?

The most frequent records are winter storm records: 94 since 1996. The rank column places the county among Wyoming's counties by days with a record per 1,000 square miles of land over each hazard's complete period.

Source: NOAA NCEI Storm Events Database (county and forecast-zone records attributed to the county; a zone record shows its own totals on each county it covers). Days: dates with at least one record of the hazard in the county. Ranks: days with a record per 1,000 square miles of land (Census Bureau 2024 Gazetteer), since 1950 for tornadoes, 1955 for hail and thunderstorm wind, 1996 for the rest.

How many tornadoes has Big Horn County had?

NOAA records 33 tornadoes in Big Horn County from 1958 to 2017, the strongest rated F3, with 1 death and 2 injuries recorded in the county. That is 8th of 23 Wyoming counties by days with tornadoes per 1,000 square miles since 1950. A tornado that crossed a county line is counted in each county it touched, with the length of its path inside the county.

Counted as whole tornadoes rather than county records, the Storm Prediction Center's database holds 32 tornadoes whose track touched Big Horn County since 1950 (NOAA's county records number 33: they file a crossing tornado once per county segment, and the two databases differ on some tracks); along their whole tracks they killed 1 person.

Map of the strongest tornado tracks in Wyoming.

Source: NOAA NCEI Storm Events Database, tornado records by county (path length in the county, maximum width); ratings as published: F scale before February 1, 2007, EF scale after. Whole-track figures: NOAA Storm Prediction Center tornado database (1950-2025). SPC severe weather database.

When was the last damaging storm in Big Horn County?

The most recent record with damage, injuries or deaths is the June 8, 2021 thunderstorm wind ($27,000 in damage in 2025 dollars).

A wind gust of 79 mph was reported at the Greybull, Wyoming airport from a convective shower. The wind gust caused damage in Greybull, Wyoming, where a tree was uprooted, a roof and house under construction were damaged, and a camper was tipped over.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 964793)

Source: NOAA NCEI Storm Events Database; every record of 2025-2026 is listed, earlier ones when they caused deaths, injuries or $250,000 of damage (2025 dollars), and every tornado.

The deadliest and costliest records

A damage figure marked "step" is a record from before 1993: NOAA then filed damage by category, and the figure is the category as entered, in the dollars of that year, not an estimate of the loss.

Source: NOAA NCEI Storm Events Database: deaths and injuries direct and indirect; damage is property plus crops as estimated by the National Weather Service, converted to 2025 dollars.

Is it getting more frequent?

Records per decade for Big Horn County's most frequent hazards. Counts rose everywhere after 1996, when NOAA began recording every event type, so compare decades within a hazard's complete period only (the shaded cells come before it).

Source: NOAA NCEI Storm Events Database, records per calendar decade; zone records from the CZ_TYPE field (Z).

What time of year?

Records by month in Big Horn County. The two busiest months are in violet.

Source: NOAA NCEI Storm Events Database, records by the month they began.

Federal disaster declarations for Big Horn County

FEMA's register lists 4 declarations that include Big Horn County: 3 major disasters, one emergency and 0 fire management assistance declarations. Most were for biological (2) and severe storm (1).

Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), declarations through October 2, 2026; one declaration is counted once however many areas it names. OpenFEMA dataset page.

How many floods has Big Horn County had?

NOAA's Storm Events Database holds 30 flood or flash flood records for Big Horn County from 1997 to 2024, on 26 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Big Horn County ranks 2400th of 2,942 U.S. counties.

The National Flood Insurance Program has paid $248,000 on 9 claims filed in Big Horn County; the most in one year was 3 in 2014. Claims count insured losses only: uninsured flood damage is not in this file.

Source: FEMA OpenFEMA NFIP Redacted Claims, as of September 8, 2026; claims by year of loss, payments in the dollars of the year paid. OpenFEMA dataset page.

FEMA's modeled risk for Big Horn County

FEMA's National Risk Index rates Big Horn County Very Low overall, with an expected annual loss of $8.9 million. These are FEMA's model estimates of future loss from 18 hazards, not a count of what happened; they can differ from the record above.

Source: FEMA National Risk Index, county table, December 2025 release. FEMA's National Risk Index map.

Counties that share a border with Big Horn County

1. Park County 987
2. Sheridan County 815
3. Carbon County, MT 803
4. Big Horn County, MT 787
5. Johnson County 750
6. Big Horn County 394
7. Washakie County 370

Source: U.S. Census Bureau county adjacency file; NOAA NCEI Storm Events Database, records since 1950. The Census Bureau's adjacency file.

Next

• Tornadoes in WyomingEvery Wyoming tornado since 1950 and the counties with the most per square mile
• Winter storms in WyomingThe state's winter storm records, by county, year and month
• The Wyoming recordEvery hazard in the state, its deadliest events and its federal declarations
• FEMA's risk rating for each hazard in Big Horn CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download Big Horn County's FEMA declarations (CSV)4 rows: every declaration that named the county, for your own analysis