Columbia Falls, MT 59913 Frost Dates
Columbia Falls, MT: when does the frost end?
Around 05/18 is the usual last spring frost, about 263 days away. Fall's first freeze usually shows up around 09/20, roughly 124 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Columbia Falls in Zone 5a (-20 to -15°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 3 weeks until Columbia Falls's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Columbia Falls's last frost
05/18 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/06 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/04 and only about 1 year in 10 sees frost after that.
Columbia Falls against the rest of the dataset
Columbia Falls's growing season runs about 124 days, ranking 38,830 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 181 of 392.
Learn more
Before leaning on 59913's figures: zone vs. frost date explains why Zone 5a and Columbia Falls's frost date answer different questions, while the frost range explains how to read the range around Columbia Falls's dates instead of trusting one.