Grass Range, MT 59032 Frost Dates
When can you plant in Grass Range, MT?
The last spring frost here typically falls around 05/20, about 265 days from today. The first fall frost typically arrives around 09/24, about 126 frost-free days later.
Grass Range 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.
What to do before the first frost
About 4 weeks of growing season left in Grass Range before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
05/20 is the middle of 30 years of NOAA records, not a promise. Plant by 05/06 and you're betting against frost in roughly 9 years out of 10. 06/06 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Grass Range compares
At roughly 126 frost-free days, Grass Range places 38,733 of 40,283 ZIP codes in this dataset. Within MT, it ranks 168 of 392.
Learn more
zone vs. frost date covers why Zone 4b and Grass Range's frost date answer different questions. the frost range covers how to read the range around Grass Range's dates instead of trusting one.