Montana floods
Every recorded flood since 1996 · 56 counties with a record
NOAA's Storm Events Database records 1,175 floods and flash floods in Montana from 1996 through June 30, 2026, about 39 a year since 2000. The deadliest was the June 4, 1996 flood in Flathead County and Lake County: 3 deaths. Montana ranks 39th of 52 states and territories by count and 49th of 51 per square mile.
Floods in Montana, 1996 to 2026
Flood records per year (NOAA Storm Events); 2026 to June 30, 2026.
- recorded, no damage figure
- under $1 million
- $1 million or more
- $10 million or more
- $100 million or more, or 10 deaths
- $1 billion or more, or 100 deaths
- a year's colour: its recorded damage or deaths
- a year with a death
- Records
- 1,1751996 to June 30, 2026
- A year since 2000
- 39average
- Deaths
- 95 injuries
- Damage, 2025 dollars
- $114Mas filed
- Busiest year
- 2011227 records
Source: NOAA NCEI Storm Events Database, records through June 30, 2026; deaths and damage as filed, damage in 2025 dollars. Search the record at NCEI.
Are floods and flash floods common in Montana?
Montana averages about 39 floods and flash floods a year since 2000, 39th of 52 states and territories by count. The busiest year on record was 2011 (227). Per 10,000 square miles of land, Montana records 81 floods and flash floods since 1996, 49th of 51 states and territories by that measure.
Source: NOAA NCEI Storm Events Database, records since 1996, per 10,000 square miles of land area (Census Bureau 2024 Gazetteer; places under 1,000 square miles not ranked). Damage colours: Storm Events damage, 2025 dollars.
Which counties in Montana have the most floods and flash floods?
Per square mile, Silver Bow County leads Montana: 16 days with a flood since 1996, 22.3 per 1,000 square miles of land. By raw count, Valley County has the most flood records (123 since 1996); large counties collect more records simply by covering more ground, so the ranking counts days with a record per unit of area (a storm filed for several forecast zones adds several records but one day).
Source: NOAA NCEI Storm Events Database, days with a record in the county since 1996 per 1,000 square miles of land (Census Bureau 2024 Gazetteer); in brackets, the count of records.
When is flood season in Montana?
51% of its floods and flash floods since 1996 fell in May and June. The busiest month is June (359 records).
The values, month by month
Jan 15 · Feb 35 · Mar 170 · Apr 74 · May 244 · Jun 359 · Jul 186 · Aug 61 · Sep 10 · Oct 10 · Nov 6 · Dec 5 (records).
Source: NOAA NCEI Storm Events Database, records by the month they began, since 1996.
What were the deadliest floods and flash floods in Montana?
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 1996-06-04 | FloodFlathead County and Lake County · forecast zone West Glacier Region Major damage from flooding occurred mainly in Ravalli County were numerous roads were flooded and washed out. The worst road damage occurred on the Skalkaho Highway between the Bitterroot Valley and the Philipsburg/Anaconda area were water was diverted into the road in several places. Flooding on the Bitterroot River ... | 3 | 0 | – | |
| 2011-05-20 | FloodWashoe, Carbon County One storm episode: 9 records in 9 places, 2011-05-20 to 2011-05-21; the totals are the episode's. A Pacific low moved into the four corners region on the 17th and migrated northeast into the Dakotas through the 22nd, bringing another round of heavy precipitation aided by a tap of Gulf of Mexico moisture. Another system passed to the south on the 23rd and 24th, continuing the precipitation across the area. A new ... | 2 | 0 | $17M | |
| 2023-05-17 | FloodArmington, Cascade County BTCM8, Belt Creek near Monarch, crested at 6.79 feet on May 17th. Water levels resulted in strong currents that claimed the lives of two men visiting from Canada. The two men went into the fast moving water to retrieve their dog. The dog made it to shore, but the two men were pulled downstream and ultimately drowned. ... | 2 | 0 | $58K | |
| 2011-05-24 | Flash FloodSt Xavier, Big Horn County Water was reported to be flowing over Highway 313 near Soap Creek. Heavy rainfall impacted streams draining into the St Xavier area. In addition, a body was found in a flooded vehicle at the Koyamas Pond recreation area near the Big Horn River. | 1 | 0 | – | |
| 1996-05-16 | FloodAntrim Creek, Ravalli County An 18-month year old boy drowned in Antrim Creek near Florence, when playing along the swollen creek. He slipped into the creek and was swept away. | 1 | 0 | – |
Source: NOAA NCEI Storm Events Database: deaths direct and indirect, as filed by the National Weather Service, summed over each storm (one episode, or one named storm filed by several offices). Storm names from the titles of FEMA declarations that name the storm's counties.
The costliest floods and flash floods in Montana
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2025-12-11 | FloodYakt, Lincoln County One storm episode: 3 records in 3 places; the totals are the episode's. | 0 | 0 | $35M | |
| 2011-05-20 | FloodWashoe, Carbon County One storm episode: 9 records in 9 places, 2011-05-20 to 2011-05-21; the totals are the episode's. | 2 | 0 | $17M | |
| 2006-11-05 | Flash FloodWest Glacier, Flathead County | 0 | 0 | $10M | |
| 2011-05-23 | FloodRoundup Airport, Musselshell County | 0 | 0 | $7.9M | |
| 2023-04-12 | FloodLaredo, Hill County One storm episode: 3 records in 3 places; the totals are the episode's. | 0 | 0 | $4.8M | |
| 1997-05-01 | FloodFlathead County and 2 more · forecast zone Flathead/Mission Valleys One storm episode: 3 records in 2 places; the totals are the episode's. | 0 | 0 | $4.0M | |
| 2010-06-20 | Flash FloodLogan Airport Bill, Yellowstone County | 0 | 0 | $3.7M | |
| 1996-03-11 | FloodMissoula County and Ravalli County · forecast zone Missoula / Bitterroot Valleys One storm episode: 2 records in 2 places; the totals are the episode's. | 0 | 0 | $2.8M |
Source: NOAA NCEI Storm Events Database: property and crop damage as estimated by the National Weather Service, in 2025 dollars.
Are floods and flash floods becoming more frequent in Montana?
Montana's count per decade against the whole country's, and its share. NOAA recorded every event type only from 1996, so earlier decades are not comparable; the share of the national total is the fairer comparison across decades.
| Decade | Montana | United States | Montana's share |
|---|---|---|---|
| 1996-99 | 164 | 20,986 | 0.78% |
| 2000s | 284 | 54,913 | 0.52% |
| 2010s | 591 | 68,322 | 0.87% |
| 2020-26 | 136 | 43,563 | 0.31% |
Source: NOAA NCEI Storm Events Database.
The most recent floods and flash floods in Montana
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2026-06-29 | FloodBig Arm, Lake County | 0 | 0 | – | |
| 2026-06-29 | FloodPolebridge Sonderson, Flathead County | 0 | 0 | – | |
| 2026-06-29 | FloodBabb, Glacier County | 0 | 0 | – | |
| 2026-06-28 | FloodWestby, Sheridan County | 0 | 0 | – | |
| 2026-06-27 | Flash FloodCulbertson, Roosevelt County | 0 | 0 | – | |
| 2026-06-27 | Flash FloodJordan, Garfield County | 0 | 0 | – | |
| 2026-06-27 | Flash FloodWolf Pt, Roosevelt County | 0 | 0 | – | |
| 2026-05-29 | FloodRollins, Lake County | 0 | 0 | $4K | |
| 2026-05-28 | FloodHungry Horse, Flathead County | 0 | 0 | – | |
| 2025-12-11 | FloodThompson Falls, Sanders County | 0 | 0 | $100K | |
| 2025-12-11 | FloodLookout, Mineral County | 0 | 0 | $4.0M | |
| 2025-12-11 | FloodYakt, Lincoln County | 0 | 0 | $31M |
Source: NOAA NCEI Storm Events Database, records through June 30, 2026; the newest months are revised by NCEI as reports arrive. Search the record at NCEI.
Federal disaster declarations for floods and flash floods in Montana
FEMA has declared 27 disasters in Montana for floods and flash floods, counting its incident type and declarations that name flood in the title (FEMA files most storm disasters under Severe Storm); 26 were major disasters, the latest on April 7, 2026.
| Declared | Number | Title | Areas named |
|---|---|---|---|
| 2026-04-07 | DR-4901 | Severe Storms and Flooding | 1 |
| 2025-12-19 | EM-3630 | Severe Storms and Flooding | 3 |
| 2025-09-11 | DR-4887 | Severe Storms, Straight-Line Winds, and Flooding | 1 |
| 2024-07-18 | DR-4801 | Severe Winter Storm and Flooding | 12 |
| 2023-10-11 | DR-4745 | Flooding | 10 |
| 2023-08-12 | DR-4726 | Flooding | 8 |
| 2022-06-16 | DR-4655 | Severe Storm and Flooding | 7 |
| 2019-05-24 | DR-4437 | Flooding | 8 |
| 2018-10-31 | DR-4405 | Flooding | 9 |
| 2018-08-30 | DR-4388 | Flooding | 7 |
| 2014-10-09 | DR-4198 | Severe Storms, Straight-Line Winds, and Flooding | 6 |
| 2014-04-17 | DR-4172 | Ice Jams and Flooding | 15 |
Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), through October 2, 2026. OpenFEMA dataset page.
Next
- Silver Bow County: the county's whole recordThe Montana county with the most floods and flash floods per square mile
- Floods across the United StatesEvery state ranked, by year and month
- Every natural hazard in MontanaTornadoes, floods, storms, heat and the federal declarations
- Winter storms in Montana8,475 records
- Hail in Montana8,391 records
- High wind and dust storms in Montana7,814 records