Choteau, MT 59422 Frost Dates
Frost dates for Choteau, MT, ZIP 59422
Around 05/16 is the usual last spring frost, about 261 days away. The first fall frost typically arrives around 09/27, about 133 frost-free days later.
The USDA Plant Hardiness Zone Map puts Choteau 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
Zone 4b around Choteau 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.
The actual range around Choteau's last frost
05/16 is the middle of 30 years of NOAA records, not a promise. Plant by 05/02 and you're betting against frost in roughly 9 years out of 10. 05/28 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Choteau compares
About 133 days separate Choteau's last and first frost, putting it 38,068 of 40,283 ZIP codes nationally. Within MT, it ranks 118 of 392.
Learn more
the frost range explains how to read the range around Choteau's dates instead of trusting one, and local microclimates explains what one yard in Choteau can differ from the 59422 normal.