Polson, MT 59915 Frost Dates
Polson, MT: when does the frost end?
The last spring frost here typically falls around 05/15, about 260 days from today. Fall's first freeze usually shows up around 09/28, roughly 134 days after the last spring frost.
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.
Stretching the season past the first frost
With roughly 4 weeks until Polson's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Polson's last frost
05/15 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/03 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/01 and only about 1 year in 10 sees frost after that.
Polson against the rest of the dataset
Polson's growing season runs about 134 days, ranking 37,955 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 108 of 392.
Learn more
Before leaning on 59915's figures: local microclimates explains what one yard in Polson can differ from the 59915 normal, while zone vs. frost date explains why Zone 6a and Polson's frost date answer different questions.