Billings, MT 59108 Frost Dates
Frost dates for Billings, MT, ZIP 59108
Typically, the last spring freeze lands around 05/12, roughly 257 days out. The first fall frost typically arrives around 09/25, about 136 frost-free days later.
Billings sits in USDA Zone 5a (-20 to -15°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 5a around Billings 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.
Why 05/12 isn't a guarantee
05/12 is the middle of 30 years of NOAA records, not a promise. Plant by 04/30 and you're betting against frost in roughly 9 years out of 10. 05/26 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Billings compares
Billings's growing season runs about 136 days, ranking 37,615 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 86 of 392.
Learn more
local microclimates explains what one yard in Billings can differ from the 59108 normal, and zone vs. frost date explains why Zone 5a and Billings's frost date answer different questions.