Frost Dates for 01475 — Winchendon, Massachusetts

Half of springs at Birch Hill Dam, MA see their last 32°F night by May 6; only one in ten is past it by April 25, and one in ten still has one after May 19. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 15 20%, and after May 19 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 51% of the 71 Massachusetts stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 1 in half of years, as early as September 19 one year in ten, and holds off past October 16 one year in ten. A hard freeze of 28°F follows 11 days later, around October 12; in spring the one-in-ten date for 28°F is May 5, 14 days before the 32°F one. The freeze-free season lasts 148 days in a typical year, shorter than at 94% of the 71 Massachusetts stations; it reaches 166 days one year in ten and falls short of 131 one year in ten. On average 178 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 19, and return around September 23. Severe cold of 16°F or below comes every winter, usually between November 23 and March 24.

July is the warmest month at Birch Hill Dam, MA, averaging 82°F by day and 59°F at night; January is the coldest at 32°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 72% of years.

Warmth for growing adds up to 2,282 growing degree days a year (base 50°F), fewer than at 93% of the 71 Massachusetts stations. 31% of them (707) have built up by the end of June, and July adds the most, 623. Precipitation totals 48.6 inches a year, most in October (4.9") and least in February (3.2"); May to September bring 43% of it.

The nearest other station, Ashburnham N, MA, 6 miles east of Winchendon and 291 feet higher, has a last frost 1 day earlier (May 5), a first frost 6 days later (October 7), a season 4 days longer.

The first measurable snow (0.1 inch or more) in Winchendon usually arrives around November 29, and the last of the season around March 25. Those are the middle dates across the winters of 1991–2020 at Birch Hill Dam, MA, 4.9 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 42 days after the last snow.

ZIP 01475 is 5 miles from Birch Hill Dam, MA, which stands at 855 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 01475 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.