Anchorage, AK 99587 Frost Dates
Frost dates for Anchorage, AK, ZIP 99587
Typically, the last spring freeze lands around 05/08, roughly 253 days out. The first fall frost typically arrives around 09/29, about 142 frost-free days later.
The USDA Plant Hardiness Zone Map puts Anchorage in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 5b around Anchorage has about 5 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 05/08 isn't a guarantee
05/08 is the middle of 30 years of NOAA records, not a promise. Plant by 04/26 and you're betting against frost in roughly 9 years out of 10. 05/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Anchorage compares
About 142 days separate Anchorage's last and first frost, putting it 36,694 of 40,283 ZIP codes nationally. Within AK, it ranks 65 of 269.
Learn more
local microclimates explains what one yard in Anchorage can differ from the 99587 normal, and zone vs. frost date explains why Zone 5b and Anchorage's frost date answer different questions.