Anchorage, AK 99524 Frost Dates
Anchorage, AK: when does the frost end?
Around 05/18 is the usual last spring frost, about 263 days away. Fall's first freeze usually shows up around 09/23, roughly 125 days after the last spring frost.
Zone 5a (-20 to -15°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 Anchorage, not a forecast for this year.
Stretching the season past the first frost
With roughly 4 weeks until Anchorage's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/18 isn't a guarantee
05/18 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/04 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/31 and only about 1 year in 10 sees frost after that.
Anchorage against the rest of the dataset
About 125 days separate Anchorage's last and first frost, putting it 38,744 of 40,283 ZIP codes nationally. Within AK, it ranks 93 of 269.
Learn more
Before leaning on 99524's figures: local microclimates explains what one yard in Anchorage can differ from the 99524 normal, while zone vs. frost date explains why Zone 5a and Anchorage's frost date answer different questions.