Anchorage Forecast Office, AK Frost Dates & Growing Season

The two dates every Anchorage Forecast Office garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
May 5
~50% chance of frost after
First fall frost
Sep 29
~50% chance of frost before
Growing season
147 days
frost-free stretch
USDA zone
≈ 4b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Apr 25 May 5 May 14
First fall frost Oct 13 Sep 29 Sep 17
Hard freeze (28°F), median last Apr 22 · first Oct 9

Computed from NOAA 1991–2020 climate normals at the ANCHORAGE FORECAST OFFICE station. "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Anchorage Forecast Office

Computed from Anchorage Forecast Office's own frost dates. Click any crop for the full zone-4 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Mar 10 – Mar 24 May 12 – May 19
🫑 Peppers Feb 24 – Mar 10 May 19 – May 26
🥬 Lettuce Mar 24 – Apr 7 Apr 7 – Apr 21 Apr 7 – May 5
🫛 Peas Mar 24 – Apr 7
🥕 Carrots Apr 14 – May 5
🥦 Broccoli Mar 17 – Mar 31 Apr 14 – Apr 28
🥬 Kale Mar 24 – Apr 7 Apr 7 – Apr 21 Apr 7 – Apr 21
🥒 Cucumbers Apr 7 – Apr 14 May 12 – May 19 May 12 – May 19
🥒 Zucchini Apr 7 – Apr 14 May 12 – May 19 May 12 – May 19
🫘 Green Beans (Bush) May 12 – May 19
🌽 Sweet Corn May 12 – May 19
🌿 Basil Mar 24 – Apr 7 May 12 – May 19 May 19 – May 26
🧄 Garlic Fall: Aug 18 – Sep 15

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Anchorage Forecast Office's dates automatically after a lookup.

Reading the season in Anchorage Forecast Office

At about 147 frost-free days, Anchorage Forecast Office rewards efficiency: start warm-season crops indoors, favor short-season varieties, and lean on cold-tolerant crops — peas, kale, roots — that shrug off the shoulder-season frosts on either end.

Frequently asked questions

When is the last frost in Anchorage Forecast Office, AK?

The average last spring frost in Anchorage Forecast Office is around May 5, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Anchorage Forecast Office, AK?

The average first fall frost in Anchorage Forecast Office arrives around Sep 29. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Anchorage Forecast Office?

About 147 frost-free days on average, from May 5 to Sep 29. That favors short-season varieties and transplants for warm-season crops, with cool-season vegetables doing the heavy lifting in spring and fall.

What USDA zone is Anchorage Forecast Office in?

USDA zone 4b on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.