Anchorage, AK 99508 Frost Dates
99508, near Anchorage, AK: the frost window
The last spring frost here typically falls around 05/01, about 246 days from today. Fall's first freeze usually shows up around 09/29, roughly 150 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
Anchorage's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
05/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/19 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/09 and only about 1 year in 10 sees frost after that.
Anchorage against the rest of the dataset
At roughly 150 frost-free days, Anchorage places 35,237 of 40,283 ZIP codes in this dataset. Within AK, it ranks 49 of 269.
Learn more
Two guides worth reading on 99508: local microclimates, on what one yard in Anchorage can differ from the 99508 normal, and zone vs. frost date, on why Zone 5a and Anchorage's frost date answer different questions.