Montana inland flooding risk
Yellowstone County has the highest inland flooding risk in Montana, scoring 84.5 out of 100 — rated "Relatively Moderate" by FEMA's National Risk Index. Recorded inland flooding events across Montana have decreased 46% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Yellowstone County | 84.5 | Relatively Moderate | 8 |
| 2 | Cascade County | 83.4 | Relatively Moderate | 20 |
| 3 | Flathead County | 79.8 | Relatively Moderate | 4 |
| 4 | Carbon County | 72.3 | Relatively Low | 5 |
| 5 | Missoula County | 68.6 | Relatively Low | 19 |
| 6 | Lincoln County | 65.5 | Relatively Low | 4 |
| 7 | Lewis and Clark County | 64.6 | Relatively Low | 21 |
| 8 | Gallatin County | 64.2 | Relatively Low | 3 |
| 9 | Sanders County | 61.9 | Relatively Low | 5 |
| 10 | Lake County | 57.2 | Relatively Low | 0 |
| 11 | Rosebud County | 56.5 | Relatively Low | 1 |
| 12 | Park County | 55.6 | Relatively Low | 1 |
| 13 | Big Horn County | 55.1 | Relatively Low | 4 |
| 14 | Ravalli County | 52 | Relatively Low | 6 |
| 15 | Chouteau County | 50.4 | Relatively Low | 4 |
| 16 | Blaine County | 46.5 | Relatively Low | 11 |
| 17 | Glacier County | 45.5 | Relatively Low | 1 |
| 18 | Hill County | 43.4 | Relatively Low | 3 |
| 19 | Phillips County | 39.8 | Relatively Low | 16 |
| 20 | Custer County | 38.3 | Relatively Low | 6 |
| 21 | Fergus County | 36.5 | Relatively Low | 8 |
| 22 | Beaverhead County | 36.3 | Relatively Low | 2 |
| 23 | Stillwater County | 36.2 | Relatively Low | 9 |
| 24 | Valley County | 34.2 | Very Low | 41 |
| 25 | Teton County | 32.2 | Very Low | 4 |
| 26 | Madison County | 29.8 | Very Low | 5 |
| 27 | Jefferson County | 29.4 | Very Low | 4 |
| 28 | Pondera County | 29.3 | Very Low | 2 |
| 29 | Dawson County | 28.1 | Very Low | 8 |
| 30 | Roosevelt County | 26.6 | Very Low | 15 |
| 31 | Richland County | 25.1 | Very Low | 7 |
| 32 | Silver Bow County | 21.7 | Very Low | 3 |
| 33 | Sweet Grass County | 19.7 | Very Low | 3 |
| 34 | Broadwater County | 19.1 | Very Low | 3 |
| 35 | Toole County | 17.8 | Very Low | 2 |
| 36 | Mineral County | 16 | Very Low | 2 |
| 37 | Powell County | 15.8 | Very Low | 2 |
| 38 | Musselshell County | 15.5 | Very Low | 7 |
| 39 | Sheridan County | 13.3 | Very Low | 3 |
| 40 | Judith Basin County | 12.6 | Very Low | 2 |
| 41 | Wheatland County | 12.2 | Very Low | 1 |
| 42 | Liberty County | 11.9 | Very Low | 2 |
| 43 | Granite County | 11.1 | Very Low | 2 |
| 44 | Deer Lodge County | 10.5 | Very Low | 1 |
| 45 | Meagher County | 9.7 | Very Low | 2 |
| 46 | Powder River County | 7.8 | Very Low | 7 |
| 47 | Prairie County | 5.8 | Very Low | 7 |
| 48 | Golden Valley County | 5.6 | Very Low | 3 |
| 49 | McCone County | 5.6 | Very Low | 4 |
| 50 | Fallon County | 5.5 | Very Low | 1 |
| 51 | Garfield County | 5.4 | Very Low | 6 |
| 52 | Carter County | 4.1 | Very Low | 3 |
| 53 | Wibaux County | 3.7 | Very Low | 0 |
| 54 | Daniels County | 3 | Very Low | 5 |
| 55 | Treasure County | 2.5 | Very Low | 1 |
| 56 | Petroleum County | 2 | Very Low | 7 |
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.
Inland Flooding risk nationally:
Other hazard risks in Montana:
Frequently asked questions
What is the highest inland flooding risk county in Montana?
Yellowstone County, MT has the highest inland flooding risk in Montana, with a FEMA National Risk Index score of 84.5 out of 100 (rated "Relatively Moderate").
What causes inland flooding risk in Montana?
Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.