Pennsylvania climate

Pennsylvania Plant Hardiness Zones

Pennsylvania’s towns run from zone 5b to zone 8a: the average coldest winter night is 10.2°F at Eddystone and -14.5°F at Kane.

Hardiness zones in Pennsylvania

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 Pennsylvania, from zone 5b to zone 8a, with the state’s border drawn.
  • 5b
  • 6a
  • 6b
  • 7a
  • 7b
  • 8a

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.

8a Zone 8a, 10 to 15°F 2 towns

7b Zone 7b, 5 to 10°F 178 towns

7a Zone 7a, 0 to 5°F 482 towns

6b Zone 6b, -5 to 0°F 559 towns

6a Zone 6a, -10 to -5°F 228 towns

5b Zone 5b, -15 to -10°F 29 towns

Counties

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

CountyZone at the centerAverage coldest night
Adams County7a1.1°F
Allegheny County6b-0.5°F
Armstrong County6b-4.6°F
Beaver County6b-1.9°F
Bedford County6b-3.9°F
Berks County7a2.9°F
Blair County6a-6.3°F
Bradford County6a-7.4°F
Bucks County7a3.2°F
Butler County6a-5.9°F
Cambria County6a-9.9°F
Cameron County5b-11.4°F
Carbon County6b-3.8°F
Centre County6b-3.4°F
Chester County7a2.3°F
Clarion County6a-7.1°F
Clearfield County6a-7.8°F
Clinton County6b-4.6°F
Columbia County6b-3.9°F
Crawford County6a-5.7°F
Cumberland County7a2.3°F
Dauphin County7a0.3°F
Delaware County7b7.4°F
Elk County5b-10.9°F
Erie County7a0.4°F
Fayette County6b-4.6°F
Forest County6a-7.7°F
Franklin County7a3.4°F
Fulton County7a0.6°F
Greene County6b-4.4°F
Huntingdon County6b-2.3°F
Indiana County6b-4.4°F
Jefferson County6a-6.4°F
Juniata County7a1.6°F
Lackawanna County6b-3.6°F
Lancaster County7a4.1°F
Lawrence County6b-4.6°F
Lebanon County7a1.4°F
Lehigh County7a0.9°F
Luzerne County6b-4.3°F
Lycoming County6a-5.8°F
McKean County5b-11.1°F
Mercer County6a-7.5°F
Mifflin County7a1.6°F
Monroe County6b-4.3°F
Montgomery County7a2.7°F
Montour County6b-3.7°F
Northampton County7a0°F
Northumberland County6b-1.4°F
Perry County7a1.5°F
Philadelphia County7b8.6°F
Pike County6a-7.7°F
Potter County5b-11.7°F
Schuylkill County6b-1.9°F
Snyder County6b-1.9°F
Somerset County6a-6.8°F
Sullivan County6a-6.9°F
Susquehanna County5b-10.6°F
Tioga County5b-10.5°F
Union County6b-2.5°F
Venango County6a-5.5°F
Warren County6a-6.4°F
Washington County6b-3.2°F
Wayne County6a-9.2°F
Westmoreland County6b-4.7°F
Wyoming County6a-6°F
York County7a0.9°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
5b-15 to -10°F-26.1 to -23.3°C
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
7b5 to 10°F-15.0 to -12.2°C
8a10 to 15°F-12.2 to -9.4°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.