Columbia Falls, MT 59921 Frost Dates
Frost dates for Columbia Falls, MT, ZIP 59921
The last spring frost here typically falls around 05/18, about 263 days from today. The first fall frost typically arrives around 09/20, about 124 frost-free days later.
Columbia Falls 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.
What to do before the first frost
Zone 5a around Columbia Falls has about 3 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around Columbia Falls's last frost
05/18 is the middle of 30 years of NOAA records, not a promise. Plant by 05/06 and you're betting against frost in roughly 9 years out of 10. 06/04 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Columbia Falls compares
Columbia Falls's growing season runs about 124 days, ranking 38,831 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 182 of 392.
Learn more
the frost range explains how to read the range around Columbia Falls's dates instead of trusting one, and local microclimates explains what one yard in Columbia Falls can differ from the 59921 normal.