Debris Flow in Montana
Every debris flow event the National Weather Service has filed in Montana, year by year, with the most significant episodes. A fast-moving slurry of mud, rock and debris, usually on a slope soaked by heavy rain or stripped by a fire.
The most significant on the map
The most significant debris flow episodes in Montana.
- 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
- 18
- Deaths
- 0
- Injuries
- 2
- Damage
- $137,000
Every year
The most significant
Ranked by deaths, injuries, damage and size together.
- Tornado and Flash Flooding in Montana, June 5 to 10, 2023Several rounds of rain and thunderstorms affected much of Montana during the first half of June. Flash flooding occurred across portions of the region, especially across Fergus County as well as the Rocky Mountains.
- Flash Flood and Debris Flow in Montana, July 20, 2012Heavy rain from thunderstorms which developed over the Scratch Gravel Hills burn scar caused a debris flow which damaged a home and washed out railroad tracks.
- Debris Flow and Heavy Snow in Montana, December 28 to 29, 2011A large and complex weather system from the Pacific moved across north central Idaho to end the year. This system had 3 major impacts on the region. First, a tight surface pressure gradient, along with strong upper level winds produced high winds.
- Debris Flow in Montana, September 19, 2004A Canadian couple were injured and hospitalized when their 2003 Porsche Carrera GT was struk by falling rocks the size of basketballs on Glacier National Park's Going to the Sun road. The rock slide was caused by excessive rains over the area.
- Flash Flood and Debris Flow in Montana, June 6 to 7, 2023Anomalous atmospheric moisture combined with slow moving thunderstorms caused copious amounts of rain and in some places flooding.
- Flash Flood and Debris Flow in Montana, July 31, 2025An upper-level shortwave combined with monsoon moisture brought a few severe thunderstorms and localized areas of heavy rainfall to North-Central MT. This resulted in isolated large hail, flooding, and a landspout.
- Debris Flow and Flooding in Montana, May 28 to 31, 2026Between May 28 and June 4, 2026, a very slow-moving upper-level low-pressure system over Montana tapped into moisture from the Gulf of America, bringing heavy and widespread precipitation to western Montana.
- Flash Flood and Debris Flow in Montana, May 29, 2013Heavy thunderstorms moved across the Dahl and Chalky Fire burn scar areas.
- Debris Flow and Hail in Montana, May 21, 2023Thunderstorms developed across western Montana ahead of an approaching trough. High amounts of atmospheric moisture and slow storm motion contributed to a flash flood threat, especially over recent burn scars. A few storms produced quarter size hail.
- Debris Flow and Heavy Rain in Montana, August 1, 2025Anomalously high precipitable water (200-210% of normal) along with a shortwave trough, resulted in high rainfall rates with convection. The Weather Prediction Center issued a slight risk for excessive rainfall rates.
- Debris Flow and Heavy Rain in Montana, July 30, 2025Slow-moving thunderstorms brought torrential rainfall and triggered subsequent debris flows across parts of southwest Montana.
- Debris Flow in Montana, August 20 to 21, 2004Heavy rain from thunderstorms caused a large rock and debris slide to occur near Haystack Creek from The Loop to Logan Pass in Glacier National Park. The large slide deposited about 2,000 cubic feet of rock and debris 150 feet wide and up to 12 feet deep onto the road.
- Debris Flow in Montana, June 13, 2006Thunderstorms brought heavy rains which caused 10 mudslides across Going to the Sun Road in Glacier National Park.
- Debris Flow in Montana, July 17, 2013A series of debris flows (two significant and several minor) impacted areas north and west of Corwin Springs along U.S. Highway 89. A confluence of meteorological factors combined to create a volatile situation at the southern edge of the Paradise Valley.
- Debris Flow in Montana, September 10 to 11, 2021An upper level trough with near record atmospheric moisture levels moved around the western U.S. ridge from Oregon to northwest Montana.
- Debris Flow in Montana, August 16, 2025Intense thunderstorms brought heavy rainfall and a debris flow east of Sula.
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.