Indiana climate

Indiana Plant Hardiness Zones

Indiana’s towns run from zone 5b to zone 7a: the average coldest winter night is 4.7°F at Tell City and -11.8°F at Lowell.

Hardiness zones in Indiana

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 Indiana, 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 37 towns

6b Zone 6b, -5 to 0°F 103 towns

6a Zone 6a, -10 to -5°F 321 towns

5b Zone 5b, -15 to -10°F 32 towns

Counties

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

CountyZone at the centerAverage coldest night
Adams County6a-6.8°F
Allen County6a-7.2°F
Bartholomew County6b-2.9°F
Benton County5b-10.5°F
Blackford County6a-8°F
Boone County6a-7.6°F
Brown County6b-4.6°F
Carroll County6a-8.6°F
Cass County6a-7.9°F
Clark County7a1.9°F
Clay County6a-5.6°F
Clinton County6a-7.8°F
Crawford County6b-3.6°F
Daviess County6b-2.5°F
Dearborn County6b-3.6°F
Decatur County6b-3.7°F
DeKalb County6a-7.3°F
Delaware County6a-6.8°F
Dubois County6b-1.8°F
Elkhart County6a-7.5°F
Fayette County6a-6°F
Floyd County6b-0.3°F
Fountain County6a-8.8°F
Franklin County6b-5°F
Fulton County6a-8°F
Gibson County6b-0.1°F
Grant County6a-7.1°F
Greene County6b-4.3°F
Hamilton County6a-6.6°F
Hancock County6a-6.9°F
Harrison County7a0.4°F
Hendricks County6a-7.4°F
Henry County6a-8.3°F
Howard County6a-9°F
Huntington County6a-7.8°F
Jackson County6b-2.8°F
Jasper County5b-10.2°F
Jay County6a-7.4°F
Jefferson County6b-4.4°F
Jennings County6b-4.6°F
Johnson County6b-5°F
Knox County6b-2.2°F
Kosciusko County6a-7.7°F
LaGrange County6a-7.8°F
Lake County6a-9.2°F
LaPorte County6a-8.8°F
Lawrence County6b-4.5°F
Madison County6a-6.9°F
Marion County6b-4.2°F
Marshall County6a-7.9°F
Martin County6b-3.2°F
Miami County6a-8.3°F
Monroe County6b-3.8°F
Montgomery County5b-10.1°F
Morgan County6a-6.2°F
Newton County5b-10.1°F
Noble County6a-7.8°F
Ohio County6b-4.1°F
Orange County6b-4.5°F
Owen County6a-5.6°F
Parke County6a-7.8°F
Perry County7a0.8°F
Pike County6b-1.1°F
Porter County6a-9°F
Posey County7a1.6°F
Pulaski County6a-9.8°F
Putnam County6a-7.4°F
Randolph County6a-7.9°F
Ripley County6b-4.9°F
Rush County6a-6.5°F
Saint Joseph County6a-8.5°F
Scott County6b-1.8°F
Shelby County6b-4.7°F
Spencer County7a1.6°F
Starke County5b-11.1°F
Steuben County6a-8.5°F
Sullivan County6b-3.9°F
Switzerland County6b-3.1°F
Tippecanoe County6a-8.9°F
Tipton County6a-8.3°F
Union County6a-7.2°F
Vanderburgh County7a2°F
Vermillion County6a-7.6°F
Vigo County6a-5.1°F
Wabash County6a-7.7°F
Warren County6a-9.5°F
Warrick County7a0.2°F
Washington County6b-3.1°F
Wayne County6a-8.2°F
Wells County6a-7.4°F
White County6a-9.8°F
Whitley County6a-8.3°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

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.