Idaho heat wave risk
Ada County has the highest heat wave risk in Idaho, scoring 92.9 out of 100 — rated "Relatively Moderate" by FEMA's National Risk Index. NOAA has recorded 26 heat wave events across Idaho over the past decade.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Ada County | 92.9 | Relatively Moderate | 0 |
| 2 | Canyon County | 89.5 | Relatively Moderate | 1 |
| 3 | Bingham County | 86 | Relatively Moderate | 4 |
| 4 | Kootenai County | 83.1 | Relatively Moderate | 1 |
| 5 | Twin Falls County | 82.7 | Relatively Moderate | 0 |
| 6 | Bonneville County | 81.2 | Relatively Moderate | 0 |
| 7 | Jefferson County | 79.1 | Relatively Moderate | 0 |
| 8 | Bannock County | 79 | Relatively Moderate | 0 |
| 9 | Madison County | 77 | Relatively Low | 3 |
| 10 | Jerome County | 72.9 | Relatively Low | 0 |
| 11 | Minidoka County | 71.7 | Relatively Low | 0 |
| 12 | Blaine County | 64.3 | Relatively Low | 0 |
| 13 | Elmore County | 58.7 | Relatively Low | 0 |
| 14 | Cassia County | 56.6 | Relatively Low | 0 |
| 15 | Gooding County | 56.2 | Relatively Low | 0 |
| 16 | Nez Perce County | 56.1 | Relatively Low | 1 |
| 17 | Bonner County | 53.9 | Relatively Low | 1 |
| 18 | Latah County | 51.3 | Relatively Low | 1 |
| 19 | Payette County | 48.5 | Relatively Low | 1 |
| 20 | Owyhee County | 48.2 | Relatively Low | 0 |
| 21 | Gem County | 44.3 | Relatively Low | 1 |
| 22 | Power County | 40.7 | Relatively Low | 0 |
| 23 | Lincoln County | 40.2 | Relatively Low | 0 |
| 24 | Washington County | 38.3 | Very Low | 0 |
| 25 | Idaho County | 37.9 | Very Low | 3 |
| 26 | Boundary County | 30.9 | Very Low | 1 |
| 27 | Shoshone County | 30.6 | Very Low | 1 |
| 28 | Fremont County | 29.4 | Very Low | 0 |
| 29 | Butte County | 27.7 | Very Low | 0 |
| 30 | Clearwater County | 27.5 | Very Low | 4 |
| 31 | Benewah County | 27 | Very Low | 1 |
| 32 | Franklin County | 26.6 | Very Low | 0 |
| 33 | Custer County | 20.5 | Very Low | 4 |
| 34 | Lewis County | 19.3 | Very Low | 0 |
| 35 | Adams County | 18.3 | Very Low | 0 |
| 36 | Valley County | 17.6 | Very Low | 0 |
| 37 | Oneida County | 17.1 | Very Low | 0 |
| 38 | Boise County | 14.9 | Very Low | 0 |
| 39 | Lemhi County | 12.5 | Very Low | 1 |
| 40 | Teton County | 9.7 | Very Low | 0 |
| 41 | Caribou County | 9.1 | Very Low | 0 |
| 42 | Camas County | 8.6 | Very Low | 0 |
| 43 | Bear Lake County | 5.5 | Very Low | 0 |
| 44 | Clark County | 4.9 | 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 Idaho:
Frequently asked questions
What is the highest heat wave risk county in Idaho?
Ada County, ID has the highest heat wave risk in Idaho, with a FEMA National Risk Index score of 92.9 out of 100 (rated "Relatively Moderate").
What causes heat wave risk in Idaho?
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.