Flash Flood in Wyoming
Every flash flood event the National Weather Service has filed in Wyoming, year by year, with the most significant episodes. Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
The most significant on the map
The most significant flash flood episodes in Wyoming.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The record
- Events
- 375
- Deaths
- 5
- Injuries
- 6
- Damage
- $22 million
Every year
The most significant
Ranked by deaths, injuries, damage and size together.
- Flash Flood in Wyoming, July 19, 2011Debris carried down by runoff from heavy rainfall clogged a drainage culvert on a small section of Highway 130, resulting in the water washing away the pavement around the culvert shortly after midnight on July 19.
- Tornado and Flash Flood in Wyoming, August 12, 2005A tornado touched down 1 mile north of Wright and traveled southeast into the town.
- Tornadoes and Flash Flood in Wyoming, May 22, 2008Severe thunderstorms moved generally north northwest over parts of far southeast Wyoming producing a few tornadoes as well as hail and some flooding. The most significant tornado tracked across southeastern Albany county into northern and eastern parts of the city of Laramie.
- Flash Flood and Hail in Wyoming, July 22, 2008A severe thunderstorm clipped far northern portions of Campbell and Crook Counties with hail to golf ball size and heavy rain. Three to six inches of rain fell from near Weston to the Wyoming/Montana border.
- Tornadoes and Flash Flooding in Wyoming, May 18, 2010Southeast low level wind flow increased ahead of a low pressure system over northern Colorado the afternoon of May 18 2010. A strong low level southeast jet combined with dynamics of the low to create a favorable environment for severe thunderstorms.
- Flash Flood and Hail in Wyoming, August 1, 2013A supercell thunderstorm moved southeastward across southern Campbell County, producing large hail and strong wind gusts. Extensive hail damage occurred in Wright, with many homes and vehicles affected, with the Noonan and Casner subdivisions receiving the most damage.
- Flash Flood and Damaging Wind in Wyoming, July 3, 2009Intense rainfall accompanied a strong thunderstorm which gained strength just west of Casper before blasting through town. The thunderstorm formed in a uncharacteristically moist airmass where precipitable water values approached 150% of normal.
- Tornadoes and Flash Flood in Wyoming, June 12 to 17, 2017A combination of an abnormally strong upper level low, strong jet dynamics and an approaching cold front produced one of the biggest severe weather outbreaks across western and central Wyoming in many years.
- Flash Flooding and Hail in Wyoming, June 4, 2015Thunderstorms across much of southeast Wyoming produced widespread large hail as well as some flash flooding from torrential rainfall. The worst flooding occurred during the predawn hours across southern Niobrara County from Manville to Lusk to Van Tassel.
- Flash Flood in Wyoming, June 15, 2023On June 15th, roughly between 300 PM and 415 PM MDT, slow moving thunderstorms fueled by a wet air mass led to heavy rain over parts of Natrona County, including the city of Casper, WY and surrounding suburbs.
- Flash Flooding and Flooding in Wyoming, May 24 to 26, 2015A slow-moving upper level low south of Wyoming sent waves of moisture northward over central and eastern Wyoming during the Memorial Day holiday weekend. Measured and estimated rainfall totals ranged from two to around five inches.
- Flash Flood and Hail in Wyoming, June 25, 2026A QLCS moved quickly across central and southeast Wyoming during the middle afternoon to late afternoon hours. Most strong gusty winds were reported with a few severe hail reports.
- Flash Flood and Hail in Wyoming, July 5, 2013A moist and unstable airmass and an upper level disturbance brought a third straight day of thunderstorms to western and central Wyoming.
- Flash Flooding and Hail in Wyoming, June 3 to 4, 2015The combination of a stalled frontal boundary, jet streak dynamics, and an upper level disturbance sweeping across Wyoming created the conditions necessary to produce severe thunderstorms in central Wyoming. A moisture-laden atmosphere also set the stage for flash flooding.
- Flash Flood in Wyoming, September 12, 2013Thunderstorms dropped very heavy rain over portions of eastern Lincoln County during the late afternoon hours of September 12. Rainfall estimated at around one inch fell in a little less than one hour.
- Tornado and Flash Flood in Wyoming, July 10, 2001Eyewitnesses reported 2 brief touchdowns. Mobile home destroyed and barn damaged, approximately 1/4 mile apart. Property damage amounts unknown. Water at least 3 feet deep caused considerable damage to mobile home and fences. Three horses injured.
- Flash Flood in Wyoming, July 28, 2021Monsoon moisture moved into the state, bring abnormally high precipitable water levels. Thunderstorms formed and moved slowly within very light steering flow, with some storms becoming nearly stationary.
- Flash Flooding in Wyoming, July 25, 2007Copious moisture was brought north into Wyoming in strong monsoonal flow. Low-level upslope flow from the north aided the development of showers and thunderstorms. Atmospheric moisture values were around 200 percent of normal.
- Flash Flooding and Hail in Wyoming, July 4, 2009A storm that developed northwest of Dubois traveled along the Wind River Valley and walloped central Fremont County with hail and heavy rain. Hail up to several inches deep accumulated on U.S. Highway 26 northwest of Riverton near Kinnear.
- Flash Flood and Hail in Wyoming, July 25, 2005A line of strong thunderstorms moved west to east across Natrona County between 4:30 p.m. and 6:30 p.m.
- Flash Flood in Wyoming, August 2 to 3, 2007Thunderstorms producing heavy rain formed northwest of Casper during the late evening. The storms tracked southeast along and south of U.S. Highway 20/26 over areas that had been hard hit by heavy rain over the previous two weeks.
- Flash Flood in Wyoming, August 26 to 27, 2002A stationary thunderstorm brought flash flooding and an estimated 3 inches of rain to Kaycee. Most of the rain fell between midnight and 4 AM MDT. The flooding did damage to 19 trailers and 22 houses.
- Flash Flood in Wyoming, May 28, 2001Heavy rain began falling over the Donkey Creek drainage, just south of Gillette, around 5 pm MST. Rainfall rates over 2 inches per hour were recorded. A National Weather Service spotter recorded a storm total precipitation amount of 7.5 inches during the evening.
- Flash Flood in Wyoming, July 10, 2001Flash flooding along Line Creek. Mobile home, outbuildings destroyed; homes flooded and roads and bridges washed out in the Line Creek subdivision. Property damage estimated by emergency management official.
- Flash Flood in Wyoming, July 16, 2002Strong thunderstorms caused flash flooding across portions of southern Park County. The first area of flash flooding and damage was reported near Valley. Heavy rain washed out bridges and portions of gravel roads.
More
Sources
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24.