Frost Dates for 05679 — Williamstown, Vermont

Half of springs at Barre Montpelier Airport, VT see their last 32°F night by May 16; only one in ten is past it by May 2, and one in ten still has one after May 30. Planting tender crops after May 22 leaves a 30% risk of a frost on them, after May 26 20%, and after May 30 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 54% of the 41 Vermont stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 29 in half of years, as early as September 16 one year in ten, and holds off past October 12 one year in ten. A hard freeze of 28°F follows 10 days later, around October 9; in spring the one-in-ten date for 28°F is May 17, 13 days before the 32°F one. The freeze-free season lasts 136 days in a typical year, shorter than at 76% of the 41 Vermont stations; it reaches 155 days one year in ten and falls short of 117 one year in ten. On average 169 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 30, and return around September 20. Severe cold of 16°F or below comes every winter, usually between November 15 and April 3.

July is the warmest month at Barre Montpelier Airport, VT, averaging 78°F by day and 56°F at night; January is the coldest at 26°F and 7°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 1,821 growing degree days a year (base 50°F), fewer than at 78% of the 41 Vermont stations. 30% of them (544) have built up by the end of June, and July adds the most, 513. Precipitation totals 38.7 inches a year, most in July (4.3") and least in February (2.1"); May to September bring 49% of it.

The nearest other station, Northfield, VT, 7 miles northwest of Williamstown and 456 feet lower, has a last frost 2 days later (May 18), a first frost 1 day earlier (September 28), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Williamstown usually arrives around November 14, and the last of the season around April 8. Those are the middle dates across the winters of 1991–2020 at Northfield, VT, 6.9 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 38 days after the last snow.

ZIP 05679 is 7 miles from Barre Montpelier Airport, VT, which stands at 1,126 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 05641 (Barre). The 2023 USDA Plant Hardiness Zone Map lists ZIP 05679 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.