Frost Dates for 01550 — Southbridge, Massachusetts

Half of springs at Southbridge 3 SW, MA see their last 32°F night by April 25; only one in ten is past it by April 14, and one in ten still has one after May 8. Planting tender crops after May 1 leaves a 30% risk of a frost on them, after May 4 20%, and after May 8 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 13 in half of years, as early as October 2 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 12 days later, around October 25; in spring the one-in-ten date for 28°F is April 24, 14 days before the 32°F one. The freeze-free season lasts 168 days in a typical year, shorter than at 52% of the 71 Massachusetts stations; it reaches 186 days one year in ten and falls short of 152 one year in ten. On average 147 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 11 days longer, to about May 6, and return around October 4. Severe cold of 16°F or below comes every winter, usually between December 1 and March 15.

July is the warmest month at Southbridge 3 SW, MA, averaging 81°F by day and 60°F at night; January is the coldest at 35°F and 17°F. A freezing night is all but certain in every month from October 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 32% of years.

Warmth for growing adds up to 2,437 growing degree days a year (base 50°F), fewer than at 80% of the 71 Massachusetts stations. 31% of them (765) have built up by the end of June, and July adds the most, 628. Precipitation totals 51.8 inches a year, most in December (5.1") and least in February (3.5"); May to September bring 41% of it.

The nearest other station, E Brimfield Lake, MA, 5 miles northwest of Southbridge, has a last frost 3 days later (April 28), a first frost 2 days later (October 15), a season 1 day longer.

The first measurable snow (0.1 inch or more) in Southbridge usually arrives around December 4, and the last of the season around March 22. Those are the middle dates across the winters of 1991–2020 at Southbridge 3 SW, 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 34 days after the last snow.

ZIP 01550 is 2 miles from Southbridge 3 SW, MA, which stands at 685 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 01550 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.