Frost Dates for 59644 — Townsend, Montana

Half of springs at Townsend 3SE, MT see their last 32°F night by May 19; only one in ten is past it by May 8, and one in ten still has one after June 2. Planting tender crops after May 25 leaves a 30% risk of a frost on them, after May 28 20%, and after June 2 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 19 in half of years, as early as September 5 one year in ten, and holds off past October 2 one year in ten. A hard freeze of 28°F follows 12 days later, around October 1; in spring the one-in-ten date for 28°F is May 20, 13 days before the 32°F one. The freeze-free season lasts 122 days in a typical year, shorter than at 57% of the 68 Montana stations; it reaches 140 days one year in ten and falls short of 103 one year in ten. On average 174 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 17 days longer, to about June 5, and return around September 7. Severe cold of 16°F or below comes every winter, usually between October 31 and March 31.

July is the warmest month at Townsend 3SE, MT, averaging 83°F by day and 52°F at night; January is the coldest at 34°F and 14°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 12% of years.

Warmth for growing adds up to 1,839 growing degree days a year (base 50°F), fewer than at 54% of the 68 Montana stations. 27% of them (503) have built up by the end of June, and July adds the most, 544. Precipitation totals 10.7 inches a year, most in June (2.5") and least in January (0.3"); May to September bring 69% of it.

The nearest other station, Tizer Gardens, MT, 27 miles west of Townsend and 708 feet higher, has a last frost 30 days later (June 18), a first frost 14 days earlier (September 5), a season 41 days shorter.

The first measurable snow (0.1 inch or more) in Townsend usually arrives around November 7, and the last of the season around April 18. Those are the middle dates across the winters of 1991–2020 at Townsend 3SE, MT, 6.6 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 31 days after the last snow.

ZIP 59644 is 7 miles from Townsend 3SE, MT, which stands at 3,964 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 59644 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.