Anchorage, AK 99520 Frost Dates
Anchorage, AK: when does the frost end?
Typically, the last spring freeze lands around 05/18, roughly 263 days out. Fall's first freeze usually shows up around 09/23, roughly 125 days after the last spring frost.
Anchorage sits in USDA Zone 5b (-15 to -10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
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
At roughly 125 frost-free days, Anchorage places 38,740 of 40,283 ZIP codes in this dataset. Within AK, it ranks 89 of 269.
Learn more
Before leaning on 99520's figures: local microclimates explains what one yard in Anchorage can differ from the 99520 normal, while zone vs. frost date explains why Zone 5b and Anchorage's frost date answer different questions.