Polson, MT 59860 Frost Dates
When can you plant in Polson, MT?
Typically, the last spring freeze lands around 05/10, roughly 255 days out. The first fall frost typically arrives around 10/05, about 147 frost-free days later.
Polson sits in USDA Zone 6a (-10 to -5°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
About 5 weeks of growing season left in Polson before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/10 isn't a guarantee
05/10 is the middle of 30 years of NOAA records, not a promise. Plant by 04/27 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 Polson compares
About 147 days separate Polson's last and first frost, putting it 35,896 of 40,283 ZIP codes nationally. Within MT, it ranks 30 of 392.
Learn more
the frost range covers how to read the range around Polson's dates instead of trusting one. local microclimates covers what one yard in Polson can differ from the 59860 normal.