Kachemak, AK 99639 Frost Dates
99639, near Kachemak, AK: the frost window
Around 05/16 is the usual last spring frost, about 261 days away. Fall's first freeze usually shows up around 09/30, roughly 136 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Kachemak in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Kachemak'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.
Why 05/16 isn't a guarantee
05/16 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/30 and only about 1 year in 10 sees frost after that.
Kachemak against the rest of the dataset
Kachemak's growing season runs about 136 days, ranking 37,748 of 40,283 US ZIP codes measured here, longest to shortest. Within AK, it ranks 73 of 269.
Learn more
Two guides worth reading on 99639: the frost range, on how to read the range around Kachemak's dates instead of trusting one, and local microclimates, on what one yard in Kachemak can differ from the 99639 normal.