Alaska Plant Hardiness Zones by Town (USDA 2023)

Hardiness zones in Alaska

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 Alaska, from zone 1a to zone 8b, with the state’s border drawn.

1a
1b
2a
2b
3a
3b
4a
4b
5a
5b
6a
6b
7a
7b
8a
8b

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 3 towns

8a Zone 8a, 10 to 15°F 6 towns

7b Zone 7b, 5 to 10°F 7 towns

7a Zone 7a, 0 to 5°F 6 towns

6b Zone 6b, -5 to 0°F 4 towns

6a Zone 6a, -10 to -5°F 4 towns

5b Zone 5b, -15 to -10°F 4 towns

5a Zone 5a, -20 to -15°F 16 towns

4b Zone 4b, -25 to -20°F 19 towns

4a Zone 4a, -30 to -25°F 19 towns

3b Zone 3b, -35 to -30°F 5 towns

3a Zone 3a, -40 to -35°F 5 towns

2b Zone 2b, -45 to -40°F 5 towns

2a Zone 2a, -50 to -45°F 15 towns

1b Zone 1b, -55 to -50°F 2 towns

1a Zone 1a, -60 to -55°F 1 towns

Fort Yukon-57.9°F

Counties

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

County	Zone at the center	Average coldest night
Aleutians East Borough	7a	4.4°F
Aleutians West Census Area	8a	13.7°F
Anchorage Municipality	5a	-18.1°F
Bethel Census Area	3b	-30.1°F
Bristol Bay Borough	4b	-24.5°F
Chugach Census Area	6b	-0.4°F
City and Borough of Wrangell	7a	2.6°F
Copper River Census Area	2b	-42.5°F
Denali Borough	2b	-42.6°F
Dillingham Census Area	4a	-27.2°F
Fairbanks North Star Borough	3b	-32.5°F
Haines Borough	6a	-7.3°F
Hoonah-Angoon Census Area	7a	4.6°F
Juneau City and Borough	5a	-16.9°F
Kenai Peninsula Borough	4b	-20.5°F
Ketchikan Gateway Borough	7b	9.4°F
Kodiak Island Borough	6a	-7.8°F
Kusilvak Census Area	4a	-26.6°F
Lake and Peninsula Borough	5a	-15.7°F
Matanuska-Susitna Borough	4b	-22°F
Nome Census Area	4a	-27.1°F
North Slope Borough	2a	-49.7°F
Northwest Arctic Borough	2b	-43.4°F
Petersburg Borough	7b	5.5°F
Prince of Wales-Hyder Census Area	7b	8°F
Sitka City and Borough	7b	7.2°F
Skagway Municipality	6b	-2.3°F
Southeast Fairbanks Census Area	3a	-39.4°F
Yakutat City and Borough	6a	-9.3°F
Yukon-Koyukuk Census Area	2b	-44.9°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.

Zone	Average coldest night	In Celsius
1a	-60 to -55°F	-51.1 to -48.3°C
1b	-55 to -50°F	-48.3 to -45.6°C
2a	-50 to -45°F	-45.6 to -42.8°C
2b	-45 to -40°F	-42.8 to -40.0°C
3a	-40 to -35°F	-40.0 to -37.2°C
3b	-35 to -30°F	-37.2 to -34.4°C
4a	-30 to -25°F	-34.4 to -31.7°C
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
7a	0 to 5°F	-17.8 to -15.0°C
7b	5 to 10°F	-15.0 to -12.2°C
8a	10 to 15°F	-12.2 to -9.4°C
8b	15 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.