Ohio heat wave risk
Franklin County has the highest heat wave risk in Ohio, scoring 98.9 out of 100 — rated "Relatively High" by FEMA's National Risk Index. Recorded heat wave events across Ohio have decreased 88% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Franklin County | 98.9 | Relatively High | 2 |
| 2 | Hamilton County | 98.9 | Relatively High | 4 |
| 3 | Cuyahoga County | 97.7 | Relatively High | 0 |
| 4 | Scioto County | 90.9 | Relatively Moderate | 2 |
| 5 | Summit County | 90.3 | Relatively Moderate | 0 |
| 6 | Lawrence County | 90 | Relatively Moderate | 0 |
| 7 | Montgomery County | 88.7 | Relatively Moderate | 3 |
| 8 | Clermont County | 86.7 | Relatively Moderate | 3 |
| 9 | Lucas County | 85.3 | Relatively Moderate | 0 |
| 10 | Stark County | 84.7 | Relatively Moderate | 0 |
| 11 | Gallia County | 84.4 | Relatively Moderate | 0 |
| 12 | Butler County | 81.7 | Relatively Moderate | 3 |
| 13 | Licking County | 79.4 | Relatively Moderate | 2 |
| 14 | Fairfield County | 79.3 | Relatively Moderate | 2 |
| 15 | Mahoning County | 78.4 | Relatively Low | 0 |
| 16 | Ross County | 78 | Relatively Low | 2 |
| 17 | Delaware County | 76.6 | Relatively Low | 2 |
| 18 | Trumbull County | 75.6 | Relatively Low | 0 |
| 19 | Athens County | 73.8 | Relatively Low | 0 |
| 20 | Jackson County | 72.8 | Relatively Low | 0 |
| 21 | Medina County | 69.1 | Relatively Low | 0 |
| 22 | Richland County | 68.5 | Relatively Low | 0 |
| 23 | Pike County | 68.2 | Relatively Low | 2 |
| 24 | Wayne County | 68.1 | Relatively Low | 0 |
| 25 | Lake County | 67.1 | Relatively Low | 0 |
| 26 | Meigs County | 66 | Relatively Low | 0 |
| 27 | Warren County | 65.8 | Relatively Low | 3 |
| 28 | Tuscarawas County | 65.6 | Relatively Low | 0 |
| 29 | Greene County | 65.4 | Relatively Low | 2 |
| 30 | Portage County | 65.2 | Relatively Low | 0 |
| 31 | Brown County | 64.9 | Relatively Low | 3 |
| 32 | Washington County | 64.5 | Relatively Low | 1 |
| 33 | Adams County | 64.2 | Relatively Low | 3 |
| 34 | Highland County | 64.2 | Relatively Low | 3 |
| 35 | Lorain County | 64.1 | Relatively Low | 0 |
| 36 | Clark County | 63.2 | Relatively Low | 2 |
| 37 | Muskingum County | 62.8 | Relatively Low | 0 |
| 38 | Columbiana County | 60.5 | Relatively Low | 0 |
| 39 | Clinton County | 59.8 | Relatively Low | 2 |
| 40 | Holmes County | 58.6 | Relatively Low | 0 |
| 41 | Knox County | 58.5 | Relatively Low | 0 |
| 42 | Pickaway County | 58.5 | Relatively Low | 2 |
| 43 | Belmont County | 57.9 | Relatively Low | 0 |
| 44 | Geauga County | 55 | Relatively Low | 0 |
| 45 | Allen County | 51.9 | Relatively Low | 0 |
| 46 | Jefferson County | 51.4 | Relatively Low | 0 |
| 47 | Ashtabula County | 51 | Relatively Low | 0 |
| 48 | Coshocton County | 50.4 | Relatively Low | 0 |
| 49 | Ashland County | 49.4 | Relatively Low | 0 |
| 50 | Union County | 49.2 | Relatively Low | 2 |
| 51 | Hocking County | 48.3 | Relatively Low | 2 |
| 52 | Guernsey County | 47.7 | Relatively Low | 0 |
| 53 | Perry County | 47.4 | Relatively Low | 0 |
| 54 | Wood County | 47.4 | Relatively Low | 0 |
| 55 | Fayette County | 46.3 | Relatively Low | 3 |
| 56 | Vinton County | 41.9 | Relatively Low | 0 |
| 57 | Miami County | 41.7 | Relatively Low | 2 |
| 58 | Marion County | 40.2 | Relatively Low | 0 |
| 59 | Erie County | 39.2 | Relatively Low | 0 |
| 60 | Sandusky County | 37.8 | Very Low | 0 |
| 61 | Fulton County | 35 | Very Low | 0 |
| 62 | Seneca County | 34.4 | Very Low | 0 |
| 63 | Carroll County | 34.2 | Very Low | 0 |
| 64 | Preble County | 33.8 | Very Low | 2 |
| 65 | Williams County | 33.8 | Very Low | 0 |
| 66 | Huron County | 33.6 | Very Low | 0 |
| 67 | Ottawa County | 33.2 | Very Low | 0 |
| 68 | Morgan County | 32.5 | Very Low | 0 |
| 69 | Madison County | 32 | Very Low | 2 |
| 70 | Auglaize County | 30.8 | Very Low | 2 |
| 71 | Shelby County | 30.6 | Very Low | 2 |
| 72 | Monroe County | 29.7 | Very Low | 0 |
| 73 | Hancock County | 29.6 | Very Low | 0 |
| 74 | Darke County | 29.3 | Very Low | 2 |
| 75 | Noble County | 28.7 | Very Low | 0 |
| 76 | Logan County | 27.9 | Very Low | 2 |
| 77 | Defiance County | 27.4 | Very Low | 0 |
| 78 | Morrow County | 27.2 | Very Low | 0 |
| 79 | Harrison County | 26.8 | Very Low | 0 |
| 80 | Champaign County | 26.4 | Very Low | 2 |
| 81 | Crawford County | 26.2 | Very Low | 0 |
| 82 | Putnam County | 25.9 | Very Low | 0 |
| 83 | Henry County | 23.9 | Very Low | 0 |
| 84 | Hardin County | 23.5 | Very Low | 2 |
| 85 | Van Wert County | 20.6 | Very Low | 0 |
| 86 | Mercer County | 17.4 | Very Low | 2 |
| 87 | Wyandot County | 17.4 | Very Low | 0 |
| 88 | Paulding County | 17.1 | 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 Ohio:
Frequently asked questions
What is the highest heat wave risk county in Ohio?
Franklin County, OH has the highest heat wave risk in Ohio, with a FEMA National Risk Index score of 98.9 out of 100 (rated "Relatively High").
What causes heat wave risk in Ohio?
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.