Opheim, MT 59260 Frost Dates
Opheim, MT: when does the frost end?
Typically, the last spring freeze lands around 06/05, roughly 281 days out. Fall's first freeze usually shows up around 09/02, roughly 89 days after the last spring frost.
Opheim sits in USDA Zone 3b (-35 to -30°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
With roughly 1 week until Opheim's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Opheim's last frost
06/05 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/23 and only about 1 year in 10 sees frost after that.
Opheim against the rest of the dataset
Opheim's growing season runs about 89 days, ranking 39,938 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 342 of 392.
Learn more
Before leaning on 59260's figures: zone vs. frost date explains why Zone 3b and Opheim's frost date answer different questions, while the frost range explains how to read the range around Opheim's dates instead of trusting one.