Whitefish, MT 59937 Frost Dates
Whitefish, MT: when does the frost end?
Around 05/16 is the usual last spring frost, about 261 days away. Fall's first freeze usually shows up around 09/25, roughly 129 days after the last spring frost.
Whitefish 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.
Stretching the season past the first frost
With roughly 4 weeks until Whitefish's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/16 isn't a guarantee
05/16 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/02 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/06 and only about 1 year in 10 sees frost after that.
Whitefish against the rest of the dataset
At roughly 129 frost-free days, Whitefish places 38,442 of 40,283 ZIP codes in this dataset. Within MT, it ranks 133 of 392.
Learn more
Before leaning on 59937's figures: zone vs. frost date explains why Zone 5a and Whitefish's frost date answer different questions, while the frost range explains how to read the range around Whitefish's dates instead of trusting one.