Frost Dates for 59105 — Billings, Montana

Half of springs at Billings Logan International Airport, MT see their last 32°F night by May 4; only one in ten is past it by April 20, and one in ten still has one after May 18. Planting tender crops after May 10 leaves a 30% risk of a frost on them, after May 14 20%, and after May 18 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 60% of the 68 Montana stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 7 in half of years, as early as September 26 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 9 days later, around October 16; in spring the one-in-ten date for 28°F is May 7, 11 days before the 32°F one. The freeze-free season lasts 156 days in a typical year, longer than at 99% of the 68 Montana stations; it reaches 175 days one year in ten and falls short of 136 one year in ten. On average 142 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 11 days longer, to about May 15, and return around September 28. Severe cold of 16°F or below comes every winter, usually between November 11 and March 19.

July is the warmest month at Billings Logan International Airport, MT, averaging 87°F by day and 59°F at night; January is the coldest at 36°F and 18°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 61% of years.

Warmth for growing adds up to 2,596 growing degree days a year (base 50°F), more than at 94% of the 68 Montana stations. 28% of them (731) have built up by the end of June, and July adds the most, 722. Precipitation totals 14.5 inches a year, most in May (2.4") and least in January (0.6"); May to September bring 56% of it.

The nearest other station, Billings Wtp, MT, 4 miles south of Billings and 484 feet lower, has a last frost 6 days later (May 10), a first frost 6 days earlier (October 1), a season 14 days shorter.

The first measurable snow (0.1 inch or more) in Billings usually arrives around October 12, and the last of the season around April 25. Those are the middle dates across the winters of 1991–2020 at Billings Logan International Airport, MT, 4.1 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 9 days after the last snow.

ZIP 59105 is 4 miles from Billings Logan International Airport, MT, which stands at 3,581 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 59105 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.