Seward, AK 99631 Frost Dates
When can you plant in Seward, AK?
Around 05/31 is the usual last spring frost, about 276 days away. The first fall frost typically arrives around 09/08, about 99 frost-free days later.
The USDA Plant Hardiness Zone Map puts Seward in Zone 5a (-20 to -15°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
About 2 weeks of growing season left in Seward before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/31 isn't a guarantee
05/31 is the middle of 30 years of NOAA records, not a promise. Plant by 05/19 and you're betting against frost in roughly 9 years out of 10. 06/15 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Seward compares
At roughly 99 frost-free days, Seward places 39,733 of 40,283 ZIP codes in this dataset. Within AK, it ranks 201 of 269.
Learn more
the frost range covers how to read the range around Seward's dates instead of trusting one. local microclimates covers what one yard in Seward can differ from the 99631 normal.