Frost Dates for 59875 — Victor, Montana

Half of springs at Western Ag Rsch Ctr, MT see their last 32°F night by May 23; only one in ten is past it by May 8, and one in ten still has one after June 10. Planting tender crops after May 31 leaves a 30% risk of a frost on them, after June 3 20%, and after June 10 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 68% of the 68 Montana stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 21 in half of years, as early as September 5 one year in ten, and holds off past October 4 one year in ten. A hard freeze of 28°F follows 11 days later, around October 2; in spring the one-in-ten date for 28°F is May 19, 22 days before the 32°F one. The freeze-free season lasts 118 days in a typical year, shorter than at 66% of the 68 Montana stations; it reaches 140 days one year in ten and falls short of 94 one year in ten. On average 165 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 20 days longer, to about June 12, and return around September 8. Severe cold of 16°F or below comes every winter, usually between November 6 and March 13.

July is the warmest month at Western Ag Rsch Ctr, MT, averaging 86°F by day and 50°F at night; December is the coldest at 35°F and 18°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 28% of years.

Warmth for growing adds up to 1,789 growing degree days a year (base 50°F), fewer than at 59% of the 68 Montana stations. 26% of them (468) have built up by the end of June, and July adds the most, 552. Precipitation totals 11.5 inches a year, most in June (1.7") and least in February (0.6"); May to September bring 50% of it.

The nearest other station, Stevensville, MT, 9 miles northeast of Victor and 233 feet lower, has a last frost 1 day earlier (May 22), a first frost 2 days earlier (September 19), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Victor usually arrives around November 21, and the last of the season around March 29. Those are the middle dates across the winters of 1991–2020 at Hamilton, MT, 10.3 miles away: half of years saw snow earlier, half later. Snow fell in 90% of those winters. The last 32°F night of spring typically comes 55 days after the last snow.

ZIP 59875 is 7 miles from Western Ag Rsch Ctr, MT, which stands at 3,608 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 59828 (Corvallis). The 2023 USDA Plant Hardiness Zone Map lists ZIP 59875 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.