Adak, AK 99546 Frost Dates
Frost dates for Adak, AK, ZIP 99546
Around 05/31 is the usual last spring frost, about 276 days away. The first fall frost typically arrives around 10/05, about 128 frost-free days later.
Zone 8b (15 to 20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Adak, not a forecast for this year.
What to do before the first frost
Zone 8b around Adak 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 05/31 isn't a guarantee
05/31 is the middle of 30 years of NOAA records, not a promise. Plant by 05/10 and you're betting against frost in roughly 9 years out of 10. 06/23 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Adak compares
Adak's growing season runs about 128 days, ranking 38,581 of 40,283 US ZIP codes measured here, longest to shortest. Within AK, it ranks 81 of 269.
Learn more
local microclimates explains what one yard in Adak can differ from the 99546 normal, and zone vs. frost date explains why Zone 8b and Adak's frost date answer different questions.