Nunapitchuk, AK 99641 Frost Dates
99641, near Nunapitchuk, AK: the frost window
Typically, the last spring freeze lands around 05/21, roughly 266 days out. Fall's first freeze usually shows up around 09/22, roughly 122 days after the last spring frost.
Nunapitchuk sits in USDA Zone 4a (-30 to -25°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
Nunapitchuk's growing season runs out in roughly 4 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/21 isn't a guarantee
05/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/08 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/02 and only about 1 year in 10 sees frost after that.
Nunapitchuk against the rest of the dataset
Nunapitchuk's growing season runs about 122 days, ranking 38,964 of 40,283 US ZIP codes measured here, longest to shortest. Within AK, it ranks 113 of 269.
Learn more
Two guides worth reading on 99641: zone vs. frost date, on why Zone 4a and Nunapitchuk's frost date answer different questions, and the frost range, on how to read the range around Nunapitchuk's dates instead of trusting one.