Frost Dates for 01879 — Tyngsboro, Massachusetts

Half of springs at Lowell, MA see their last 32°F night by April 30; only one in ten is past it by April 19, and one in ten still has one after May 10. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 6 20%, and after May 10 10%. The 10 days between the even-odds date and the one-in-ten date is the narrowest of the 71 Massachusetts stations behind this site's ZIP pages, so the end of frost is fairly predictable.

In fall the first 32°F night comes by October 10 in half of years, as early as September 30 one year in ten, and holds off past October 24 one year in ten. A hard freeze of 28°F follows 12 days later, around October 22; in spring the one-in-ten date for 28°F is April 29, 11 days before the 32°F one. The freeze-free season lasts 164 days in a typical year, shorter than at 59% of the 71 Massachusetts stations; it reaches 179 days one year in ten and falls short of 148 one year in ten. On average 148 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 9 days longer, to about May 9, and return around October 1. Severe cold of 16°F or below comes every winter, usually between December 1 and March 19.

July is the warmest month at Lowell, MA, averaging 85°F by day and 61°F at night; January is the coldest at 34°F and 16°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 43% of years.

Warmth for growing adds up to 2,736 growing degree days a year (base 50°F), more than at 59% of the 71 Massachusetts stations. 30% of them (833) have built up by the end of June, and July adds the most, 707. Precipitation totals 48.6 inches a year, most in October (5.0") and least in February (3.2"); May to September bring 41% of it.

The nearest other station, Nashua Cwsu, NH, 5 miles northwest of Tyngsboro, has a last frost 1 day earlier (April 29), a first frost 2 days earlier (October 8), a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Tyngsboro usually arrives around December 1, and the last of the season around March 27. Those are the middle dates across the winters of 1991–2020 at Lowell, MA, 3.4 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 34 days after the last snow.

ZIP 01879 is 3 miles from Lowell, MA, which stands at 110 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 9 other ZIP codes share the station; its figures are presented in full for 01852 (Lowell). The 2023 USDA Plant Hardiness Zone Map lists ZIP 01879 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.