Frost Dates for 01566 — Sturbridge, Massachusetts

Half of springs at E Brimfield Lake, MA see their last 32°F night by April 28; only one in ten is past it by April 14, and one in ten still has one after May 17. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 9 20%, and after May 17 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 99% of the 71 Massachusetts stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 15 in half of years, as early as October 1 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 12 days later, around October 27; in spring the one-in-ten date for 28°F is May 2, 15 days before the 32°F one. The freeze-free season lasts 169 days in a typical year, shorter than at 46% of the 71 Massachusetts stations; it reaches 190 days one year in ten and falls short of 148 one year in ten. On average 150 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 11, and return around October 4. Severe cold of 16°F or below comes every winter, usually between December 2 and March 16.

July is the warmest month at E Brimfield Lake, MA, averaging 81°F by day and 62°F at night; January is the coldest at 34°F and 16°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 40% of years.

Warmth for growing adds up to 2,517 growing degree days a year (base 50°F), fewer than at 72% of the 71 Massachusetts stations. 30% of them (768) have built up by the end of June, and July adds the most, 651. Precipitation totals 48.8 inches a year, most in October (4.9") and least in February (3.2"); May to September bring 41% of it.

The nearest other station, Southbridge 3 SW, MA, 3 miles south of Sturbridge, has a last frost 3 days earlier (April 25), a first frost 2 days earlier (October 13), a season 1 day shorter.

The first measurable snow (0.1 inch or more) in Sturbridge usually arrives around November 23, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at E Brimfield Lake, MA, 2.1 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 28 days after the last snow.

ZIP 01566 is 2 miles from E Brimfield Lake, MA, which stands at 700 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 01566 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.