Frost Dates for 01541 — Princeton, Massachusetts

Half of springs at Barre Falls Dam, MA see their last 32°F night by May 12; only one in ten is past it by April 27, and one in ten still has one after May 28. Planting tender crops after May 19 leaves a 30% risk of a frost on them, after May 23 20%, and after May 28 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 87% 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 18 one year in ten, and holds off past October 15 one year in ten. A hard freeze of 28°F follows 9 days later, around October 10; in spring the one-in-ten date for 28°F is May 15, 13 days before the 32°F one. The freeze-free season lasts 141 days in a typical year, the shortest of the 71 Massachusetts stations; it reaches 161 days one year in ten and falls short of 120 one year in ten. On average 176 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 25, and return around September 22. Severe cold of 16°F or below comes every winter, usually between November 20 and March 25.

July is the warmest month at Barre Falls Dam, MA, averaging 83°F by day and 58°F at night; January is the coldest at 35°F and 13°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 80% of years.

Warmth for growing adds up to 2,380 growing degree days a year (base 50°F), fewer than at 86% of the 71 Massachusetts stations. 31% of them (743) have built up by the end of June, and July adds the most, 634. Precipitation totals 47.8 inches a year, most in October (4.9") and least in February (3.0"); May to September bring 44% of it.

The nearest other station, Fitchburg Municipal Airport, MA, 9 miles northeast of Princeton and 477 feet lower, has a last frost 13 days earlier (April 29), a first frost 10 days later (October 11), a season 23 days longer.

The first measurable snow (0.1 inch or more) in Princeton usually arrives around November 23, and the last of the season around April 2. Those are the middle dates across the winters of 1991–2020 at Barre Falls Dam, MA, 7.6 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 40 days after the last snow.

ZIP 01541 is 8 miles from Barre Falls Dam, MA, which stands at 825 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 01543 (Rutland). The 2023 USDA Plant Hardiness Zone Map lists ZIP 01541 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.