Fairfield, MT 59477 Frost Dates
59477, near Fairfield, MT: the frost window
Typically, the last spring freeze lands around 06/02, roughly 278 days out. Fall's first freeze usually shows up around 09/10, roughly 96 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Fairfield in Zone 4b (-25 to -20°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
Fairfield's growing season runs out in roughly 2 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 06/02 isn't a guarantee
06/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/21 and only about 1 year in 10 sees frost after that.
Fairfield against the rest of the dataset
Fairfield's growing season runs about 96 days, ranking 39,799 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 325 of 392.
Learn more
Two guides worth reading on 59477: local microclimates, on what one yard in Fairfield can differ from the 59477 normal, and zone vs. frost date, on why Zone 4b and Fairfield's frost date answer different questions.