Ohio climate

Ohio Plant Hardiness Zones

Ohio’s towns run from zone 6a to zone 7a: the average coldest winter night is 2.1°F at Proctorville and -9.9°F at Apple Valley.

Hardiness zones in Ohio

In USDA’s colors, neighboring states washed out. Zones follow elevation, coasts and cities down to half a mile. Drawn by WeatherOverTime from the USDA-ARS and Oregon State University PRISM Climate Group 2023 GIS data; this is not the official USDA Plant Hardiness Zone Map.

Map of the 2023 plant hardiness zones across Ohio, from zone 5b to zone 7a, with the state’s border drawn.
  • 5b
  • 6a
  • 6b
  • 7a

Open the live map with plant hardiness zones

Towns by zone

Each town’s 1991-2020 average annual extreme minimum at its center, read from the map’s 800 m grid. Warmest zone first.

7a Zone 7a, 0 to 5°F 52 towns

6b Zone 6b, -5 to 0°F 503 towns

6a Zone 6a, -10 to -5°F 311 towns

Counties

At the county’s center; a county with hills or a coast spans several zones.

CountyZone at the centerAverage coldest night
Adams County6b-0.8°F
Allen County6a-5.2°F
Ashland County6a-6.9°F
Ashtabula County6b-0.2°F
Athens County6b-2.2°F
Auglaize County6a-5.9°F
Belmont County6b-2.8°F
Brown County6b-3.1°F
Butler County6b-3.9°F
Carroll County6b-4.8°F
Champaign County6a-5.7°F
Clark County6a-6.4°F
Clermont County6b-0.9°F
Clinton County6b-4.3°F
Columbiana County6a-5.7°F
Coshocton County6a-5.1°F
Crawford County6a-6.3°F
Cuyahoga County7a1.3°F
Darke County6a-8.8°F
Defiance County6a-6.7°F
Delaware County6a-5.1°F
Erie County6b-1.8°F
Fairfield County6b-4.9°F
Fayette County6b-4°F
Franklin County6b-1.9°F
Fulton County6a-6.8°F
Gallia County6b-0.7°F
Geauga County6a-8.5°F
Greene County6b-4.6°F
Guernsey County6b-4°F
Hamilton County6b-1.7°F
Hancock County6b-4.8°F
Hardin County6a-5.2°F
Harrison County6b-3°F
Henry County6a-5.6°F
Highland County6b-3.3°F
Hocking County6b-4.9°F
Holmes County6a-7.3°F
Huron County6a-5.8°F
Jackson County6b-1.4°F
Jefferson County6b-2.1°F
Knox County6a-8.2°F
Lake County6b-1.1°F
Lawrence County7a2.5°F
Licking County6a-7.3°F
Logan County6a-8.1°F
Lorain County7a0°F
Lucas County6b-1.7°F
Madison County6a-5.7°F
Mahoning County6a-6.8°F
Marion County6a-5.5°F
Medina County6a-5.8°F
Meigs County6b-2.4°F
Mercer County6a-6.6°F
Miami County6a-5.3°F
Monroe County6b-2.3°F
Montgomery County6b-4.7°F
Morgan County6b-5°F
Morrow County6a-7.1°F
Muskingum County6b-4.1°F
Noble County6b-3.2°F
Ottawa County6b-2.2°F
Paulding County6a-8.1°F
Perry County6a-6.9°F
Pickaway County6b-2.1°F
Pike County6b-1.4°F
Portage County6a-6.3°F
Preble County6a-7.4°F
Putnam County6a-6.2°F
Richland County6a-6.4°F
Ross County6b-2.9°F
Sandusky County6b-4.9°F
Scioto County7a0.5°F
Seneca County6a-5.4°F
Shelby County6a-7.8°F
Stark County6b-3.8°F
Summit County6b-0.3°F
Trumbull County6a-6.7°F
Tuscarawas County6b-4.3°F
Union County6a-5.2°F
Van Wert County6a-6.5°F
Vinton County6b-2.4°F
Warren County6b-3.1°F
Washington County6b-1.6°F
Wayne County6a-5.8°F
Williams County6a-7.6°F
Wood County6b-4.6°F
Wyandot County6a-5.6°F

The zones

A plant hardiness zone is set by the average of each winter’s single coldest temperature, 1991 to 2020: zones are 10°F apart and each half zone, a and b, 5°F. It says how cold a winter night usually gets, not the coldest it has ever been, and nothing about summer heat, rain or soil. Plant labels give the coldest zone a perennial survives in.

ZoneAverage coldest nightIn Celsius
6a-10 to -5°F-23.3 to -20.6°C
6b-5 to 0°F-20.6 to -17.8°C
7a0 to 5°F-17.8 to -15.0°C

Sources

Hardiness zones: USDA Plant Hardiness Zone Map, 2023, Agricultural Research Service, U.S. Department of Agriculture, from the GIS data of the PRISM Climate Group, Oregon State University, which may be freely reproduced and redistributed. Drawn by WeatherOverTime from the USDA-ARS and Oregon State University PRISM Climate Group 2023 GIS data; this is not the official USDA Plant Hardiness Zone Map.