Mullan, ID 83802 Frost Dates
83802, near Mullan, ID: the frost window
Typically, the last spring freeze lands around 05/12, roughly 257 days out. Fall's first freeze usually shows up around 09/30, roughly 138 days after the last spring frost.
Mullan sits in USDA Zone 6b (-5 to 0°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
Mullan'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 05/12 isn't a guarantee
05/12 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 06/19 and only about 1 year in 10 sees frost after that.
Mullan against the rest of the dataset
Mullan's growing season runs about 138 days, ranking 37,433 of 40,283 US ZIP codes measured here, longest to shortest. Within ID, it ranks 153 of 320.
Learn more
Two guides worth reading on 83802: local microclimates, on what one yard in Mullan can differ from the 83802 normal, and zone vs. frost date, on why Zone 6b and Mullan's frost date answer different questions.