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Flood in Johnson County, Wyoming
38 floods and flash floods events in the NCEI Storm Events record, 1950 to 2026. Event types counted: Flood, Flash Flood, Coastal Flood, Lakeshore Flood.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. Storm records through 30 Jun 2026.
NCEI records 38 flood events in Johnson County, Wyoming, between 1950 and 2026, spread over 19 years.
May is the busiest month, with 14 of the recorded events. The last 20 years account for 24 events against 14 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 6.7% of the 568 flood events recorded in Wyoming; its 0.9 per 100 square miles compares with 0.6 statewide.
Compared with Wyoming
| Measure | Johnson County | Wyoming | US |
|---|---|---|---|
| Flood events since 1950 | 38 | 568 | 183,559 |
| Per 100 square miles | 0.9 | 0.6 | 5.2 |
| Per 10,000 residents | 44.1 | 9.8 | 5.5 |
| Deaths recorded | 0 | 6 | 2,961 |
| Busiest month | May | June | June |
By year
Seasonality
0Feb
0Mar
0Apr
0May
14Jun
10Jul
9Aug
4Sep
1Oct
0Nov
0Dec
0
Recorded events
All 38 events, most recent first. Magnitude is hail size, tornado rating or wind speed as recorded.
| Date | Event type | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|
| 4 Sep 2023 | Flash Flood | — | — | — | — | — | County |
| 4 Jun 2023 | Flash Flood | — | — | — | — | — | County |
| 4 Jun 2023 | Flood | — | — | — | — | — | County |
| 27 May 2019 | Flood | — | — | — | — | — | County |
| 27 May 2019 | Flood | — | — | — | — | — | County |
| 28 May 2018 | Flood | — | — | — | — | — | County |
| 28 May 2018 | Flood | — | — | — | — | — | County |
| 12 Jun 2017 | Flash Flood | — | — | — | — | — | County |
| 3 Jun 2015 | Flash Flood | — | $10K | — | — | — | County |
| 3 Jun 2015 | Flash Flood | — | $1.5M | — | — | — | County |
| 3 Jun 2015 | Flash Flood | — | — | — | — | — | County |
| 25 May 2015 | Flood | — | $5K | — | — | — | County |
| 24 May 2015 | Flood | — | $50K | $250K | — | — | County |
| 24 May 2015 | Flash Flood | — | — | — | — | — | County |
| 24 May 2015 | Flood | — | — | — | — | — | County |
| 24 May 2014 | Flash Flood | — | — | — | — | — | County |
| 5 Jul 2013 | Flash Flood | — | $50K | — | — | — | County |
| 4 Jul 2013 | Flash Flood | — | — | $10K | — | — | County |
| 12 Jul 2011 | Flash Flood | — | — | — | — | — | County |
| 8 Jun 2010 | Flood | — | — | — | — | — | County |
| 12 Jul 2009 | Flash Flood | — | $5K | — | — | — | County |
| 22 May 2008 | Flood | — | — | — | — | — | County |
| 22 May 2008 | Flood | — | $50K | — | — | — | County |
| 19 Jul 2007 | Flash Flood | — | $50K | $2K | — | — | County |
| 7 Aug 2006 | Flash Flood | — | $1K | — | — | — | County |
| 19 Jun 2003 | Flash Flood | — | $60K | — | — | — | County |
| 26 Aug 2002 | Flash Flood | — | — | — | — | — | County |
| 26 Aug 2002 | Flash Flood | — | $459K | — | — | — | County |
| 21 Aug 2002 | Flash Flood | — | — | — | — | — | County |
| 10 Jul 2001 | Flash Flood | — | — | — | — | — | County |
| 10 Jul 2001 | Flash Flood | — | $18K | — | — | — | County |
| 17 May 2000 | Flash Flood | — | — | — | — | — | County |
| 17 May 2000 | Flash Flood | — | — | — | — | — | County |
| 17 May 2000 | Flash Flood | — | — | — | — | — | County |
| 30 Jul 1998 | Flash Flood | — | — | — | — | — | County |
| 30 Jul 1998 | Flash Flood | — | — | — | — | — | County |
| 8 Jun 1997 | Flash Flood | — | — | — | — | — | County |
| 8 Jun 1997 | Flash Flood | — | — | — | — | — | County |
Questions and answers
How many flood events has Johnson County had?
38 events in the NCEI Storm Events record between 1950 and 2026. Reporting of floods and flash floods became far more complete after 1996, so early decades undercount.
When was the last recorded flood event in Johnson County?
4 Sep 2023 (Flash Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Johnson County?
The flash flood of 3 Jun 2015, with property damage estimated by NCEI at $1.5M.
How does Johnson County compare with Wyoming for flood?
0.9 events per 100 square miles against 0.6 statewide; the county holds 38 of the state's 568 recorded events.
Provenance
NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026, public domain. County-recorded events plus zone-recorded events whose forecast zone is named for the county (marked "Forecast zone"). Population and area from the US Census Bureau (2021). Built 1 Oct 2026. See the methodology, the Flood hub and the county page.