Butte-Silver Bow, MT 59707 Frost Dates
When can you plant in Butte-Silver Bow, MT?
The last spring frost here typically falls around 06/13, about 289 days from today. The first fall frost typically arrives around 09/05, about 83 frost-free days later.
The USDA Plant Hardiness Zone Map puts Butte-Silver Bow in Zone 4b (-25 to -20°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
About 1 week of growing season left in Butte-Silver Bow before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 06/13 isn't a guarantee
06/13 is the middle of 30 years of NOAA records, not a promise. Plant by 05/27 and you're betting against frost in roughly 9 years out of 10. 07/01 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Butte-Silver Bow compares
At roughly 83 frost-free days, Butte-Silver Bow places 40,013 of 40,283 ZIP codes in this dataset. Within MT, it ranks 354 of 392.
Learn more
local microclimates covers what one yard in Butte-Silver Bow can differ from the 59707 normal. zone vs. frost date covers why Zone 4b and Butte-Silver Bow's frost date answer different questions.