Frost Dates for 59937 — Whitefish, Montana

Half of springs at Whitefish, MT see their last 32°F night by May 16; only one in ten is past it by May 2, and one in ten still has one after June 6. Planting tender crops after May 25 leaves a 30% risk of a frost on them, after May 30 20%, and after June 6 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 90% of the 68 Montana stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by September 25 in half of years, as early as September 8 one year in ten, and holds off past October 8 one year in ten. A hard freeze of 28°F follows 12 days later, around October 7; in spring the one-in-ten date for 28°F is May 14, 23 days before the 32°F one. The freeze-free season lasts 129 days in a typical year, longer than at 54% of the 68 Montana stations; it reaches 150 days one year in ten and falls short of 101 one year in ten. On average 195 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 22 days longer, to about June 7, and return around September 10. Severe cold of 16°F or below comes every winter, usually between November 11 and March 17.

July is the warmest month at Whitefish, MT, averaging 81°F by day and 50°F at night; January is the coldest at 29°F and 16°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 15% of years.

Warmth for growing adds up to 1,456 growing degree days a year (base 50°F), fewer than at 90% of the 68 Montana stations. 24% of them (354) have built up by the end of June, and July adds the most, 478. Precipitation totals 20.1 inches a year, most in June (3.2") and least in August (0.9"); May to September bring 44% of it.

The nearest other station, Kalispell Glacier Airport, MT, 11 miles southeast of Whitefish, has a last frost 15 days later (May 31), a first frost 15 days earlier (September 10), a season 29 days shorter.

The first measurable snow (0.1 inch or more) in Whitefish usually arrives around November 16, and the last of the season around April 3. Those are the middle dates across the winters of 1991–2020 at Whitefish, MT, 3.3 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 43 days after the last snow.

ZIP 59937 is 3 miles from Whitefish, MT, which stands at 3,100 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 59912 (Columbia Falls). The 2023 USDA Plant Hardiness Zone Map lists ZIP 59937 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.