Frost Dates for 01776 — Sudbury, Massachusetts

Half of springs at Maynard 2, MA see their last 32°F night by May 2; only one in ten is past it by April 22, and one in ten still has one after May 16. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 12 20%, and after May 16 10%. The 14 days between the even-odds date and the one-in-ten date is wider than at 51% of the 71 Massachusetts stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 6 in half of years, as early as September 25 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 12 days later, around October 18; in spring the one-in-ten date for 28°F is May 5, 11 days before the 32°F one. The freeze-free season lasts 156 days in a typical year, shorter than at 87% of the 71 Massachusetts stations; it reaches 174 days one year in ten and falls short of 137 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 13, and return around September 27. Severe cold of 16°F or below comes every winter, usually between November 26 and March 17.

July is the warmest month at Maynard 2, MA, averaging 87°F by day and 60°F at night; January is the coldest at 37°F and 15°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 58% of years.

Warmth for growing adds up to 2,872 growing degree days a year (base 50°F), more than at 76% of the 71 Massachusetts stations. 32% of them (921) have built up by the end of June, and July adds the most, 730. Precipitation totals 49.9 inches a year, most in October (5.1") and least in February (3.3"); May to September bring 40% of it.

The nearest other station, Natick, MA, 8 miles southeast of Sudbury, has a last frost 6 days earlier (April 26), a first frost 6 days later (October 12), a season 13 days longer.

The first measurable snow (0.1 inch or more) in Sudbury usually arrives around December 6, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Natick, MA, 8.4 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 01776 is 3 miles from Maynard 2, MA, which stands at 205 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 10 other ZIP codes share the station; its figures are presented in full for 01752 (Marlborough). The 2023 USDA Plant Hardiness Zone Map lists ZIP 01776 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.