Kalispell, MT 59920 Frost Dates
Kalispell, MT: when does the frost end?
Around 05/12 is the usual last spring frost, about 257 days away. Fall's first freeze usually shows up around 09/25, roughly 134 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Kalispell in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 4 weeks until Kalispell's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Kalispell against the rest of the dataset
At roughly 134 frost-free days, Kalispell places 37,939 of 40,283 ZIP codes in this dataset. Within MT, it ranks 105 of 392.
Learn more
Before leaning on 59920's figures: zone vs. frost date explains why Zone 5b and Kalispell's frost date answer different questions, while the frost range explains how to read the range around Kalispell's dates instead of trusting one.