Johnson County, Wyoming

What hazards hit Johnson County most?

The most frequent records are winter storm records: 243 since 1996. 41% of its winter storm records since 1996 fell in March and April. 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 Johnson County had?

NOAA records 23 tornadoes in Johnson County from 1971 to 2023, the strongest rated EF2, with 0 deaths and 2 injuries recorded in the county. That is 12th 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 22 tornadoes whose track touched Johnson County since 1950 (NOAA's county records number 23: they file a crossing tornado once per county segment, and the two databases differ on some tracks); along their whole tracks they killed 0 people.

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 Johnson County?

The most recent record with damage, injuries or deaths is the August 21, 2024 wildfire ($11.8 million in damage in 2025 dollars).

The House Draw fire was sparked by by a lightning strike on the afternoon of August 21. Wind gusting to 40 mph spread the fire rapidly to the north and south of the ignition point, eventually consuming around 175000 acres before being mostly contained by August 30. At the height of the fire, Interstate 90 was closed for several hours to the east of Buffalo. Although no homes were lost in the fire, damage was extensive to ranch infrastructure with around 600 miles of fence burned along with the loss of storage and water tanks, outbuildings, feed., and equipment. Losses on private land alone were estimated by an unnamed source in the Green River Star local newspaper to be 25 million dollars, not including losses to public land and highway infrastructure. Have included this number as a preliminary damage cost estimate.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1212150)

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 Johnson 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).

High wind and dust storms in the 2010s: 65 records against 16 in the decade before, 65 of them forecast-zone records. Cells marked z rose mostly through zone records. The local National Weather Service office files these once per forecast zone, so a change in how it draws its zones or splits a storm into records moves this count as much as the weather does; read it beside the Johnson County days with a record above.

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

What time of year?

41% of its winter storm records since 1996 fell in March and April. The two busiest months are in violet.

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

Federal disaster declarations for Johnson County

FEMA's register lists 7 declarations that include Johnson County: 5 major disasters, one emergency and one fire management assistance declaration. Most were for fire (2) and biological (2).

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 Johnson County had?

NOAA's Storm Events Database holds 40 flood or flash flood records for Johnson County from 1996 to 2023, on 26 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Johnson County ranks 2523rd of 2,942 U.S. counties.

The National Flood Insurance Program has paid $22,000 on 6 claims filed in Johnson County; the most in one year was 2 in 2015. 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 Johnson County

FEMA's National Risk Index rates Johnson County Very Low overall, with an expected annual loss of $6.8 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 Johnson County

1. Campbell County 1,488
2. Natrona County 1,333
3. Converse County 843
4. Sheridan County 815
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 Johnson CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download Johnson County's FEMA declarations (CSV)7 rows: every declaration that named the county, for your own analysis