Bozeman, MT 59771 Frost Dates
When can you plant in Bozeman, MT?
Typically, the last spring freeze lands around 05/23, roughly 268 days out. The first fall frost typically arrives around 09/23, about 123 frost-free days later.
Zone 5a (-20 to -15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Bozeman, not a forecast for this year.
What to do before the first frost
About 4 weeks of growing season left in Bozeman before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Bozeman's last frost
05/23 is the middle of 30 years of NOAA records, not a promise. Plant by 05/05 and you're betting against frost in roughly 9 years out of 10. 06/12 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Bozeman compares
About 123 days separate Bozeman's last and first frost, putting it 38,879 of 40,283 ZIP codes nationally. Within MT, it ranks 194 of 392.
Learn more
local microclimates covers what one yard in Bozeman can differ from the 59771 normal. zone vs. frost date covers why Zone 5a and Bozeman's frost date answer different questions.