Old Harbor, AK 99643 Frost Dates
99643, near Old Harbor, AK: the frost window
The last spring frost here typically falls around 05/05, about 250 days from today. Fall's first freeze usually shows up around 10/03, roughly 151 days after the last spring frost.
Old Harbor sits in USDA Zone 7b (5 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
Old Harbor'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
05/05 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 05/21 and only about 1 year in 10 sees frost after that.
Old Harbor against the rest of the dataset
About 151 days separate Old Harbor's last and first frost, putting it 35,177 of 40,283 ZIP codes nationally. Within AK, it ranks 42 of 269.
Learn more
Two guides worth reading on 99643: the frost range, on how to read the range around Old Harbor's dates instead of trusting one, and local microclimates, on what one yard in Old Harbor can differ from the 99643 normal.