Frost Dates for 01721 — Ashland, Massachusetts

Half of springs at Natick, MA see their last 32°F night by April 26; only one in ten is past it by April 14, and one in ten still has one after May 9. Planting tender crops after May 1 leaves a 30% risk of a frost on them, after May 4 20%, and after May 9 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 12 in half of years, as early as October 1 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 24; in spring the one-in-ten date for 28°F is April 24, 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 186 days one year in ten and falls short of 152 one year in ten. On average 143 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 7, 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 Natick, MA, averaging 82°F by day and 62°F at night; January is the coldest at 35°F and 18°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 34% of years.

Warmth for growing adds up to 2,568 growing degree days a year (base 50°F), fewer than at 62% of the 71 Massachusetts stations. 30% of them (780) have built up by the end of June, and July adds the most, 674. Precipitation totals 47.3 inches a year, most in October (4.8") and least in February (3.1"); May to September bring 42% of it.

The nearest other station, West Medway, MA, 9 miles south of Ashland, has a last frost 4 days later (April 30), a first frost 3 days earlier (October 9), a season 7 days shorter.

The first measurable snow (0.1 inch or more) in Ashland 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, 6.1 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 36 days after the last snow.

ZIP 01721 is 6 miles from Natick, MA, which stands at 180 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 12 other ZIP codes share the station; its figures are presented in full for 01702 (Framingham). The 2023 USDA Plant Hardiness Zone Map lists ZIP 01721 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.