Utah climate

Utah Plant Hardiness Zones

Utah’s towns run from zone 4b to zone 8b: the average coldest winter night is 19.2°F at Leeds and -25°F at Randolph.

Hardiness zones in Utah

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 Utah, from zone 4a to zone 9a, with the state’s border drawn.
  • 4a
  • 4b
  • 5a
  • 5b
  • 6a
  • 6b
  • 7a
  • 7b
  • 8a
  • 8b
  • 9a

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.

8b Zone 8b, 15 to 20°F 7 towns

8a Zone 8a, 10 to 15°F 5 towns

7b Zone 7b, 5 to 10°F 26 towns

7a Zone 7a, 0 to 5°F 69 towns

6b Zone 6b, -5 to 0°F 33 towns

6a Zone 6a, -10 to -5°F 60 towns

5b Zone 5b, -15 to -10°F 29 towns

5a Zone 5a, -20 to -15°F 3 towns

4b Zone 4b, -25 to -20°F 1 towns

Counties

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

CountyZone at the centerAverage coldest night
Beaver County6b-1.2°F
Box Elder County6b-2.5°F
Cache County6a-5.8°F
Carbon County6b-2.4°F
Daggett County6a-9.2°F
Davis County7a4.6°F
Duchesne County6a-9.4°F
Emery County6b-1.9°F
Garfield County7a4.4°F
Grand County7a1.5°F
Iron County6a-9.8°F
Juab County6a-6.9°F
Kane County7a3.5°F
Millard County6a-8.7°F
Morgan County6a-6.2°F
Piute County6a-9.9°F
Rich County4b-21.5°F
Salt Lake County7b6°F
San Juan County7a0.5°F
Sanpete County5b-10.3°F
Sevier County6a-6.6°F
Summit County5b-13.4°F
Tooele County6b-3.3°F
Uintah County5b-13.7°F
Utah County7a2.5°F
Wasatch County5b-10.5°F
Washington County7a3.9°F
Wayne County7a1.9°F
Weber County6b-1.9°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
4b-25 to -20°F-31.7 to -28.9°C
5a-20 to -15°F-28.9 to -26.1°C
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
8b15 to 20°F-9.4 to -6.7°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.