Frost Dates for 59714 — Belgrade, Montana

Half of springs at Bozeman Gallatin Field, MT see their last 32°F night by May 26; only one in ten is past it by May 11, and one in ten still has one after June 12. Planting tender crops after June 2 leaves a 30% risk of a frost on them, after June 5 20%, and after June 12 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 62% of the 68 Montana stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 16 in half of years, as early as September 2 one year in ten, and holds off past September 29 one year in ten. A hard freeze of 28°F follows 12 days later, around September 28; in spring the one-in-ten date for 28°F is May 24, 19 days before the 32°F one. The freeze-free season lasts 112 days in a typical year, shorter than at 76% of the 68 Montana stations; it reaches 132 days one year in ten and falls short of 88 one year in ten. On average 198 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 21 days longer, to about June 16, and return around September 4. Severe cold of 16°F or below comes every winter, usually between October 29 and April 2.

July is the warmest month at Bozeman Gallatin Field, MT, averaging 85°F by day and 49°F at night; December is the coldest at 32°F and 10°F. A freezing night is all but certain in every month from September 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 33% of years.

Warmth for growing adds up to 1,695 growing degree days a year (base 50°F), fewer than at 74% of the 68 Montana stations. 24% of them (409) have built up by the end of June, and July adds the most, 540. Precipitation totals 13.2 inches a year, most in June (2.5") and least in January (0.4"); May to September bring 58% of it.

The nearest other station, Logan Landfill, MT, 11 miles west of Belgrade and 184 feet lower, has the same 50% last-frost date, a first frost 1 day earlier (September 15), a season 1 day shorter.

The first measurable snow (0.1 inch or more) in Belgrade usually arrives around October 7, and the last of the season around May 11. Those are the middle dates across the winters of 1991–2020 at Bozeman Montana State Univ, MT, 14.7 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 15 days after the last snow.

ZIP 59714 is 5 miles from Bozeman Gallatin Field, MT, which stands at 4,427 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 59714 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.