Frost Dates for 03576 — Colebrook, New Hampshire

Half of springs at Colebrook 3SW, NH see their last 32°F night by May 31; only one in ten is past it by May 16, and one in ten still has one after June 14. Planting tender crops after June 4 leaves a 30% risk of a frost on them, after June 8 20%, and after June 14 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 25% of the 51 New Hampshire stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 21 in half of years, as early as September 7 one year in ten, and holds off past October 2 one year in ten. A hard freeze of 28°F follows 10 days later, around October 1; in spring the one-in-ten date for 28°F is May 31, 14 days before the 32°F one. The freeze-free season lasts 112 days in a typical year, the shortest of the 51 New Hampshire stations; it reaches 130 days one year in ten and falls short of 92 one year in ten. On average 191 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 10 days longer, to about June 10, and return around September 7. Severe cold of 16°F or below comes every winter, usually between November 3 and April 11.

July is the warmest month at Colebrook 3SW, NH, averaging 77°F by day and 52°F at night; January is the coldest at 24°F and 0°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 44% of years.

Warmth for growing adds up to 1,527 growing degree days a year (base 50°F), the fewest of the 51 New Hampshire stations. 28% of them (432) have built up by the end of June, and July adds the most, 456. Precipitation totals 41.3 inches a year, most in June (4.7") and least in February (2.0"); May to September bring 50% of it.

The nearest other station, N Stratford, NH, 16 miles southwest of Colebrook and 170 feet lower, has a last frost 12 days earlier (May 19), a first frost 8 days later (September 29), a season 19 days longer.

The first measurable snow (0.1 inch or more) in Colebrook usually arrives around November 8, and the last of the season around April 16. Those are the middle dates across the winters of 1991–2020 at Colebrook 3SW, NH, 5 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 45 days after the last snow.

ZIP 03576 is 5 miles from Colebrook 3SW, NH, which stands at 1,120 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 03576 in zone 4a, the band where the coldest night of the year averaged -30 to -25°F (-34.4 to -31.7°C) over 1991–2020; a zone describes winter lows, not frost dates.