Port Heiden, AK 99549 Frost Dates
99549, near Port Heiden, AK: the frost window
Typically, the last spring freeze lands around 05/11, roughly 256 days out. Fall's first freeze usually shows up around 10/18, roughly 160 days after the last spring frost.
Port Heiden 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
Port Heiden's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Port Heiden's last frost
05/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/26 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/25 and only about 1 year in 10 sees frost after that.
Port Heiden against the rest of the dataset
Port Heiden's growing season runs about 160 days, ranking 32,549 of 40,283 US ZIP codes measured here, longest to shortest. Within AK, it ranks 30 of 269.
Learn more
Two guides worth reading on 99549: the frost range, on how to read the range around Port Heiden's dates instead of trusting one, and local microclimates, on what one yard in Port Heiden can differ from the 99549 normal.