Bozeman, MT 59027 Frost Dates
Frost dates for Bozeman, MT, ZIP 59027
Around 05/19 is the usual last spring frost, about 264 days away. The first fall frost typically arrives around 09/25, about 125 frost-free days later.
The USDA Plant Hardiness Zone Map puts Bozeman in Zone 5a (-20 to -15°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
Zone 5a around Bozeman has about 4 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
05/19 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. 06/11 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Bozeman compares
About 125 days separate Bozeman's last and first frost, putting it 38,745 of 40,283 ZIP codes nationally. Within MT, it ranks 169 of 392.
Learn more
zone vs. frost date explains why Zone 5a and Bozeman's frost date answer different questions, and the frost range explains how to read the range around Bozeman's dates instead of trusting one.