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Home Garden Lot: Garden & Home Improvement

What Hardiness Zone Is Alaska?

USDA 2023 Plant Hardiness Zone Map · 272 ZIP codes · Data updated 2026-10-28

Quick answer

Alaska spans USDA hardiness zones 1a–8b on the 2023 Plant Hardiness Zone Map. The most common zone is 5a, covering 12% of Alaska's ZIP codes, followed by zone 4a (11%). Zone 5a means the coldest night of an average winter reaches −20°F to −15°F (−29°C to −26°C). Enter your ZIP code for your exact zone.

Alaska hardiness zones by share of ZIP codes

Zone 1a2% · 5 ZIPs
Zone 1b4% · 11 ZIPs
Zone 2a10% · 27 ZIPs
Zone 2b6% · 17 ZIPs
Zone 3a7% · 18 ZIPs
Zone 3b10% · 26 ZIPs
Zone 4a11% · 31 ZIPs
Zone 4b10% · 28 ZIPs
Zone 5a12% · 33 ZIPs
Zone 5b6% · 15 ZIPs
Zone 6a1% · 4 ZIPs
Zone 6b3% · 8 ZIPs
Zone 7a8% · 21 ZIPs
Zone 7b6% · 15 ZIPs
Zone 8a3% · 9 ZIPs
Zone 8b1% · 4 ZIPs

What the zones mean for Alaska gardeners

  • Coldest and warmest towns: among towns with NOAA weather stations, Chicken (1,800 ft) is in zone 1b, while Dutch Harbor (10 ft) is in zone 8b. That is a difference of about 70°F in the coldest night of a typical winter.
  • Same zone, different frost dates: within zone 5a, the median last spring frost ranges from April 21 at Skagway Airport to June 12 at Cooper Landing 5 W, 52 days apart. Your zone tells you which perennials survive winter; your frost dates tell you when to plant.

Typical frost dates in each Alaska zone

Medians across NOAA weather stations in each zone. Colder zones usually have later spring frosts, but local terrain can shift the dates by weeks.

ZoneLast spring frostFirst fall frostStations
2aMay 20September 45
4aMay 29September 123
4bMay 20September 213
5aMay 16September 258
5bMay 7September 296
6bMay 10October 13
7aMay 15October 78
7bMay 1October 133
8aApril 18October 253

Hardiness zones for Alaska cities

Zones at the National Weather Service stations, mostly city airports, with their median frost dates.
Anchorage Lake Hood Airport5b−15°F to −10°F90May 1Oct 3
Anchorage Merrill Field5a−20°F to −15°F138May 1Sep 29
Barrow Post Rogers Airport2b−45°F to −40°F31Any monthAny month
Bethel Airport4a−30°F to −25°F102May 21Sep 22
Cold Bay Airport7a0°F to 5°F78May 25Oct 4
Deering Airport3a−40°F to −35°F21Any monthAny month
Gustavus7a0°F to 5°F40May 30Sep 16
Iliamna Airport4b−25°F to −20°F143May 10Oct 1
Kaltag Airport2a−50°F to −45°F181May 25Sep 3
Kivalina Airport3a−40°F to −35°F10Jun 10Sep 11
Klawock Airport7b5°F to 10°F12Apr 29Oct 16
Metlakatla 6 S8a10°F to 15°F105Apr 14Oct 25
Nuiqsut Airport2a−50°F to −45°F57Any monthAny month
Port Alsworth 1 SW4a−30°F to −25°F321Jun 2Sep 12
Seldovia Airport6b−5°F to 0°F29May 10Oct 1
Seward Airport5b−15°F to −10°F22May 2Oct 7
Skagway Airport5a−20°F to −15°F20Apr 21Oct 17
St George Island Airport7a0°F to 5°F125May 31Oct 5
St Paul Island Airport6b−5°F to 0°F35Jun 4Sep 28
Tanana Calhoun Memorial Airport1b−55°F to −50°F227May 29Aug 28
Wainwright Airport2b−45°F to −40°F30Any monthAny month

Hardiness zones for 56 towns in Alaska

Each NOAA weather station is shown with the USDA zone of the nearest ZIP code (within 8 miles). Coldest night is the zone's range for the average annual extreme minimum temperature. Click a column to sort.
Alyeska5b−15°F to −10°F272May 8Sep 29
Anchorage Forecast Office5b−15°F to −10°F131May 5Sep 29
Anchorage Lake Hood Airport5b−15°F to −10°F90May 1Oct 3
Anchorage Merrill Field5a−20°F to −15°F138May 1Sep 29
Anderson Lake5a−20°F to −15°F458May 16Sep 23
Annex Creek6a−10°F to −5°F92May 3Oct 14
Aurora2a−50°F to −45°F443May 16Sep 6
Barrow Post Rogers Airport2b−45°F to −40°F31Any monthAny month
Bethel Airport4a−30°F to −25°F102May 21Sep 22
Cannery Creek5a−20°F to −15°F85May 16Oct 3
Chicken1b−55°F to −50°F1,800Any monthAny month
Clear Sky2a−50°F to −45°F646May 24Sep 4
Cold Bay Airport7a0°F to 5°F78May 25Oct 4
College Obsy2b−45°F to −40°F597May 18Sep 6
Cooper Landing 5 W5a−20°F to −15°F375Jun 12Sep 1
Deering Airport3a−40°F to −35°F21Any monthAny month
Dutch Harbor8b15°F to 20°F10May 6Oct 18
Eagle River Nature Center5a−20°F to −15°F520May 16Sep 20
Eielson Field2a−50°F to −45°F547May 20Sep 1
Elfin Cove7a0°F to 5°F20Apr 26Nov 1
Ester3b−35°F to −30°F655May 24Sep 1
Fort Richardson Wtp5a−20°F to −15°F470May 9Sep 26
Galena1b−55°F to −50°F152May 18Sep 8
Glen Alps5b−15°F to −10°F2,202May 18Sep 23
Gustavus7a0°F to 5°F40May 30Sep 16
Homer 8 NW6a−10°F to −5°F1,080May 16Sep 30
Hoonah7a0°F to 5°F130May 9Oct 4
Hope5b−15°F to −10°F180May 18Sep 24
Hyder6b−5°F to 0°F80May 4Oct 11
Iliamna Airport4b−25°F to −20°F143May 10Oct 1
Juneau Dwtn7a0°F to 5°F50Apr 20Oct 22
Kaltag Airport2a−50°F to −45°F181May 25Sep 3
Kivalina Airport3a−40°F to −35°F10Jun 10Sep 11
Klawock Airport7b5°F to 10°F12Apr 29Oct 16
Lazy Mountain5a−20°F to −15°F733May 22Sep 16
McKinley Park3b−35°F to −30°F2,070Jun 6Aug 25
Metlakatla 6 S8a10°F to 15°F105Apr 14Oct 25
N Pole2a−50°F to −45°F475May 18Sep 5
Nuiqsut Airport2a−50°F to −45°F57Any monthAny month
Ouzinkie7b5°F to 10°F40May 9Oct 4
Pelican7a0°F to 5°F12May 4Oct 19
Point Baker8a10°F to 15°F20Apr 19Oct 25
Port Alexander8a10°F to 15°F12Apr 18Nov 5
Port Alsworth 1 SW4a−30°F to −25°F321Jun 2Sep 12
Seldovia Airport6b−5°F to 0°F29May 10Oct 1
Seward Airport5b−15°F to −10°F22May 2Oct 7
Skagway Airport5a−20°F to −15°F20Apr 21Oct 17
Soldotna 5SSW4b−25°F to −20°F180Jun 11Sep 1
St George Island Airport7a0°F to 5°F125May 31Oct 5
St Paul Island Airport6b−5°F to 0°F35Jun 4Sep 28
Sterling 6SW4b−25°F to −20°F292May 20Sep 21
Tanana Calhoun Memorial Airport1b−55°F to −50°F227May 29Aug 28
Thorne Bay7b5°F to 10°F286May 1Oct 13
Wainwright Airport2b−45°F to −40°F30Any monthAny month
Wally Noerenberg Hatchery7a0°F to 5°F35May 20Oct 9
Whites Crossing4a−30°F to −25°F270May 29Sep 7

Frequently asked questions

What hardiness zone is Alaska?

Alaska is in USDA hardiness zones 1a–8b on the 2023 USDA Plant Hardiness Zone Map. Zone 5a is the most common, covering 12% of Alaska's ZIP codes, and zone 4a covers 11%. Enter your ZIP code for your exact zone.

What does zone 5a mean?

Zone 5a means the average annual extreme minimum temperature, the coldest night of a typical winter, is −20°F to −15°F (−29°C to −26°C). Perennials, shrubs and trees rated for zone 5a or colder should survive winter there.

What is the coldest hardiness zone in Alaska?

Zone 1a is the coldest zone mapped in Alaska, and zone 8b is the warmest, found around Dutch Harbor.

Did Alaska's hardiness zones change in 2023?

The USDA released a new Plant Hardiness Zone Map in November 2023, based on 1991–2020 temperatures instead of 1976–2005. About half of the United States shifted half a zone warmer. Check your ZIP code here, because plant tags and older books may still list your 2012 zone.

When should I plant in zone 5a?

Hardiness zones don't set planting dates; frost dates do. Inside zone 5a in Alaska, the median last spring frost varies from April 21 to June 12. Look up your local frost dates and plant tender crops such as tomatoes after the 10%-risk last-frost date.

Zone and frost dates: use both

Your hardiness zone answers one question: will this plant survive the winter here? Choose perennials, shrubs, trees and bulbs rated for your zone or a colder one. For vegetables and annuals, what matters is the length of the frost-free season. See Alaska frost dates by town, or get a planting calendar for your ZIP code with start-indoors, transplant and sowing dates for 30 crops.

Sources and method

Zones are from the USDA 2023 Plant Hardiness Zone Map ZIP-code files published by the PRISM Climate Group, Oregon State University, based on 1991–2020 minimum temperatures. ZIP codes are assigned to states by USPS prefix. Town zones use the ZIP code nearest each NOAA 1991–2020 Climate Normals station. This is an independent tool, not an official USDA site. Full methodology.

Hardiness zones in other states