West Yellowstone, MT 82190 Frost Dates
Frost dates for West Yellowstone, MT, ZIP 82190
Typically, the last spring freeze lands around 06/03, roughly 279 days out. The first fall frost typically arrives around 09/14, about 102 frost-free days later.
The USDA Plant Hardiness Zone Map puts West Yellowstone 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 West Yellowstone has about 2 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 West Yellowstone's last frost
06/03 is the middle of 30 years of NOAA records, not a promise. Plant by 05/18 and you're betting against frost in roughly 9 years out of 10. 06/19 is the safer bet, historically only a 1-in-10 chance of frost that late.
How West Yellowstone compares
At roughly 102 frost-free days, West Yellowstone places 39,660 of 40,283 ZIP codes in this dataset. Within MT, it ranks 295 of 392.
Learn more
the frost range explains how to read the range around West Yellowstone's dates instead of trusting one, and local microclimates explains what one yard in West Yellowstone can differ from the 82190 normal.