Butte-Silver Bow, MT 59748 Frost Dates
59748, near Butte-Silver Bow, MT: the frost window
Typically, the last spring freeze lands around 06/01, roughly 277 days out. Fall's first freeze usually shows up around 09/14, roughly 105 days after the last spring frost.
Butte-Silver Bow sits in USDA Zone 4b (-25 to -20°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
Butte-Silver Bow'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.
How much risk comes with planting early here
06/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/14 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/25 and only about 1 year in 10 sees frost after that.
Butte-Silver Bow against the rest of the dataset
About 105 days separate Butte-Silver Bow's last and first frost, putting it 39,596 of 40,283 ZIP codes nationally. Within MT, it ranks 291 of 392.
Learn more
Two guides worth reading on 59748: zone vs. frost date, on why Zone 4b and Butte-Silver Bow's frost date answer different questions, and the frost range, on how to read the range around Butte-Silver Bow's dates instead of trusting one.