Montana heat wave risk
Yellowstone County has the highest heat wave risk in Montana, scoring 72.3 out of 100 — rated "Relatively Low" by FEMA's National Risk Index. NOAA has recorded 27 heat wave events across Montana over the past decade.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Yellowstone County | 72.3 | Relatively Low | 0 |
| 2 | Dawson County | 62.5 | Relatively Low | 2 |
| 3 | Flathead County | 57.2 | Relatively Low | 1 |
| 4 | Missoula County | 53.5 | Relatively Low | 2 |
| 5 | Roosevelt County | 48.1 | Relatively Low | 1 |
| 6 | Ravalli County | 47.1 | Relatively Low | 1 |
| 7 | Richland County | 46.1 | Relatively Low | 1 |
| 8 | Cascade County | 45.8 | Relatively Low | 0 |
| 9 | Lake County | 38.7 | Very Low | 3 |
| 10 | Custer County | 38.3 | Very Low | 0 |
| 11 | Lincoln County | 37.1 | Very Low | 4 |
| 12 | Lewis and Clark County | 35.4 | Very Low | 0 |
| 13 | Big Horn County | 34.9 | Very Low | 0 |
| 14 | Rosebud County | 31.8 | Very Low | 0 |
| 15 | Sanders County | 31.1 | Very Low | 4 |
| 16 | Gallatin County | 28.8 | Very Low | 0 |
| 17 | Valley County | 25.3 | Very Low | 1 |
| 18 | Hill County | 24.7 | Very Low | 0 |
| 19 | Carbon County | 20.9 | Very Low | 0 |
| 20 | Blaine County | 20.6 | Very Low | 0 |
| 21 | Phillips County | 20.6 | Very Low | 0 |
| 22 | Fergus County | 20.3 | Very Low | 0 |
| 23 | Prairie County | 18.6 | Very Low | 0 |
| 24 | McCone County | 18 | Very Low | 0 |
| 25 | Park County | 17.7 | Very Low | 0 |
| 26 | Musselshell County | 17.6 | Very Low | 0 |
| 27 | Sheridan County | 16.9 | Very Low | 0 |
| 28 | Glacier County | 16.7 | Very Low | 0 |
| 29 | Chouteau County | 16.4 | Very Low | 0 |
| 30 | Mineral County | 15.5 | Very Low | 4 |
| 31 | Stillwater County | 14.2 | Very Low | 0 |
| 32 | Silver Bow County | 13.9 | Very Low | 0 |
| 33 | Pondera County | 13.3 | Very Low | 0 |
| 34 | Fallon County | 13.2 | Very Low | 0 |
| 35 | Wibaux County | 11.7 | Very Low | 0 |
| 36 | Toole County | 11.4 | Very Low | 0 |
| 37 | Garfield County | 10.6 | Very Low | 1 |
| 38 | Jefferson County | 10.1 | Very Low | 0 |
| 39 | Powder River County | 9.7 | Very Low | 0 |
| 40 | Teton County | 9.2 | Very Low | 0 |
| 41 | Broadwater County | 8.9 | Very Low | 0 |
| 42 | Liberty County | 8.7 | Very Low | 0 |
| 43 | Daniels County | 8.1 | Very Low | 1 |
| 44 | Carter County | 7.8 | Very Low | 0 |
| 45 | Deer Lodge County | 7.4 | Very Low | 0 |
| 46 | Judith Basin County | 7.3 | Very Low | 0 |
| 47 | Wheatland County | 6.9 | Very Low | 0 |
| 48 | Sweet Grass County | 6.6 | Very Low | 0 |
| 49 | Treasure County | 6.1 | Very Low | 0 |
| 50 | Powell County | 5.9 | Very Low | 0 |
| 51 | Madison County | 5.7 | Very Low | 0 |
| 52 | Petroleum County | 5.3 | Very Low | 0 |
| 53 | Beaverhead County | 5 | Very Low | 0 |
| 54 | Golden Valley County | 4.5 | Very Low | 0 |
| 55 | Granite County | 4.2 | Very Low | 1 |
| 56 | Meagher County | 3.9 | Very Low | 0 |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Heat Wave risk nationally:
Other hazard risks in Montana:
Frequently asked questions
What is the highest heat wave risk county in Montana?
Yellowstone County, MT has the highest heat wave risk in Montana, with a FEMA National Risk Index score of 72.3 out of 100 (rated "Relatively Low").
What causes heat wave risk in Montana?
Heat is consistently the leading cause of weather-related mortality in the US, yet it remains underrepresented in federal disaster declarations relative to its actual impact. High scores reflect a combination of extreme temperature exposure, population vulnerability (elderly, outdoor workers), and limited access to cooling infrastructure.