Frost Dates for 59079 — Shepherd, Montana

Half of springs at Huntley Exp Stn, MT see their last 32°F night by May 12; only one in ten is past it by April 30, and one in ten still has one after May 26. Planting tender crops after May 17 leaves a 30% risk of a frost on them, after May 20 20%, and after May 26 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 September 25 in half of years, as early as September 13 one year in ten, and holds off past October 8 one year in ten. A hard freeze of 28°F follows 9 days later, around October 4; in spring the one-in-ten date for 28°F is May 14, 12 days before the 32°F one. The freeze-free season lasts 136 days in a typical year, longer than at 69% of the 68 Montana stations; it reaches 153 days one year in ten and falls short of 117 one year in ten. On average 182 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 13 days longer, to about May 25, and return around September 14. Severe cold of 16°F or below comes every winter, usually between November 3 and March 28.

July is the warmest month at Huntley Exp Stn, MT, averaging 87°F by day and 55°F at night; January is the coldest at 35°F and 12°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 89% of years.

Warmth for growing adds up to 2,263 growing degree days a year (base 50°F), more than at 84% of the 68 Montana stations. 29% of them (648) have built up by the end of June, and July adds the most, 651. Precipitation totals 14.7 inches a year, most in May (2.6") and least in January (0.5"); May to September bring 59% of it.

The nearest other station, Billings Logan International Airport, MT, 16 miles southwest of Shepherd and 547 feet higher, has a last frost 8 days earlier (May 4), a first frost 12 days later (October 7), a season 20 days longer.

The first measurable snow (0.1 inch or more) in Shepherd usually arrives around October 31, and the last of the season around April 15. Those are the middle dates across the winters of 1991–2020 at Huntley Exp Stn, MT, 7.5 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 27 days after the last snow.

ZIP 59079 is 8 miles from Huntley Exp Stn, MT, which stands at 3,034 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 59079 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.