Frost Dates for 59106 — Billings, Montana

Half of springs at Billings WFO, MT see their last 32°F night by May 5; only one in ten is past it by April 23, and one in ten still has one after May 21. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 15 20%, and after May 21 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 40% of the 68 Montana stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 3 in half of years, as early as September 20 one year in ten, and holds off past October 17 one year in ten. A hard freeze of 28°F follows 11 days later, around October 14; in spring the one-in-ten date for 28°F is May 6, 15 days before the 32°F one. The freeze-free season lasts 149 days in a typical year, longer than at 91% of the 68 Montana stations; it reaches 169 days one year in ten and falls short of 130 one year in ten. On average 158 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 14 days longer, to about May 19, and return around September 23. Severe cold of 16°F or below comes every winter, usually between November 9 and March 20.

July is the warmest month at Billings WFO, MT, averaging 89°F by day and 57°F at night; January is the coldest at 37°F and 15°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 67% of years.

Warmth for growing adds up to 2,534 growing degree days a year (base 50°F), more than at 91% of the 68 Montana stations. 29% of them (741) have built up by the end of June, and July adds the most, 708. Precipitation totals 14.9 inches a year, most in May (2.5") and least in January (0.6"); May to September bring 55% of it.

The nearest other station, Billings Logan International Airport, MT, 6 miles east of Billings and 396 feet higher, has a last frost 1 day earlier (May 4), a first frost 4 days later (October 7), a season 7 days longer.

The first measurable snow (0.1 inch or more) in Billings usually arrives around October 21, and the last of the season around April 22. Those are the middle dates across the winters of 1991–2020 at Billings WFO, MT, 5.2 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 13 days after the last snow.

ZIP 59106 is 5 miles from Billings WFO, MT, which stands at 3,185 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 59102 (Billings). The 2023 USDA Plant Hardiness Zone Map lists ZIP 59106 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.