473
Recorded events
52
Counties affected
1
Direct deaths
$18.7M
Property damage
Montana flash flood history: 473 recorded events across 52 counties between 1996 and 2025.
Decade by decade
Montana flash flood history by decade
The 2000s are the busiest decade on record with 203 reported flash flood events across Montana. Earlier decades are thinner because systematic reporting for this hazard expanded over time, not because the weather was calmer.
County ranking
Counties with the most flash flood events in Montana
| Rank | County | Events | Deaths | Damage | Span |
|---|---|---|---|---|---|
| #1 | Valley County | 38 | 0 | $571K | 1996–2024 |
| #2 | Musselshell County | 26 | 0 | $200K | 1998–2023 |
| #3 | Roosevelt County | 25 | 0 | $1.3M | 1997–2021 |
| #4 | Yellowstone County | 24 | 0 | $4.3M | 1997–2023 |
| #5 | Powder River County | 23 | 0 | $2K | 2001–2025 |
| #6 | Lewis and Clark County | 21 | 0 | $759K | 1999–2024 |
| #7 | Custer County | 20 | 0 | $1.0M | 1998–2023 |
| #8 | Garfield County | 20 | 0 | $226K | 1997–2023 |
| #9 | Rosebud County | 16 | 0 | $130K | 1999–2013 |
| #10 | Richland County | 16 | 0 | $295K | 1997–2023 |
| #11 | McCone County | 16 | 0 | $223K | 1999–2019 |
| #12 | Cascade County | 15 | 0 | $300K | 2002–2025 |
| #13 | Fallon County | 14 | 0 | $0 | 1998–2022 |
| #14 | Big Horn County | 13 | 1 | $0 | 1997–2023 |
| #15 | Phillips County | 13 | 0 | $15K | 1998–2014 |
| #16 | Prairie County | 13 | 0 | $120K | 1997–2019 |
| #17 | Stillwater County | 12 | 0 | $0 | 1997–2023 |
| #18 | Carbon County | 12 | 0 | $0 | 2001–2023 |
| #19 | Dawson County | 10 | 0 | $112K | 1997–2018 |
| #20 | Ravalli County | 9 | 0 | $27K | 2001–2021 |
| #21 | Wibaux County | 8 | 0 | $30K | 1996–2011 |
| #22 | Golden Valley County | 8 | 0 | $0 | 1999–2023 |
| #23 | Daniels County | 8 | 0 | $0 | 1998–2023 |
| #24 | Petroleum County | 7 | 0 | $0 | 1997–2023 |
| #25 | Carter County | 6 | 0 | $0 | 1998–2019 |
Significant events
Deadliest flash flood events in Montana
| Date | County | Scale | Deaths | Injuries |
|---|---|---|---|---|
| May 24, 2011 | Big Horn County | — | 1 | 0 |