Frost Dates for 03470 — Winchester, New Hampshire

Half of springs at Tully Lake, MA see their last 32°F night by April 25; only one in ten is past it by April 13, and one in ten still has one after May 8. Planting tender crops after April 30 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 67% of the 51 New Hampshire stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 17 in half of years, as early as October 3 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 13 days later, around October 30; in spring the one-in-ten date for 28°F is April 26, 12 days before the 32°F one. The freeze-free season lasts 175 days in a typical year, longer than at 96% of the 51 New Hampshire stations; it reaches 195 days one year in ten and falls short of 155 one year in ten. On average 159 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 8, and return around October 5. Severe cold of 16°F or below comes every winter, usually between December 3 and March 18.

July is the warmest month at Tully Lake, MA, averaging 85°F by day and 62°F at night; January is the coldest at 33°F and 14°F. A freezing night is all but certain in every month from November 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 30% of years.

Warmth for growing adds up to 2,887 growing degree days a year (base 50°F), more than at 96% of the 51 New Hampshire stations. 32% of them (924) have built up by the end of June, and July adds the most, 736. Precipitation totals 47.6 inches a year, most in October (4.7") and least in February (2.9"); May to September bring 45% of it.

The nearest other station, Keene, NH, 11 miles north of Winchester and 169 feet lower, has a last frost 19 days later (May 14), a first frost 16 days earlier (October 1), a season 37 days shorter.

The first measurable snow (0.1 inch or more) in Winchester usually arrives around November 28, and the last of the season around April 1. Those are the middle dates across the winters of 1991–2020 at Tully Lake, MA, 11.1 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 24 days after the last snow.

ZIP 03470 is 11 miles from Tully Lake, MA, which stands at 680 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 01331 (Athol). The 2023 USDA Plant Hardiness Zone Map lists ZIP 03470 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.