Frost Dates for 05055 — Norwich, Vermont

Half of springs at Hanover, NH see their last 32°F night by May 1; only one in ten is past it by April 21, and one in ten still has one after May 15. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 10 20%, and after May 15 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 54% of the 41 Vermont stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 13 in half of years, as early as October 1 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 11 days later, around October 24; in spring the one-in-ten date for 28°F is May 3, 12 days before the 32°F one. The freeze-free season lasts 162 days in a typical year, longer than at 85% of the 41 Vermont stations; it reaches 181 days one year in ten and falls short of 146 one year in ten. On average 152 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 12 days longer, to about May 13, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 27 and March 23.

July is the warmest month at Hanover, NH, averaging 83°F by day and 61°F at night; January is the coldest at 30°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 September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 55% of years.

Warmth for growing adds up to 2,696 growing degree days a year (base 50°F), more than at 95% of the 41 Vermont stations. 32% of them (861) have built up by the end of June, and July adds the most, 687. Precipitation totals 40.1 inches a year, most in July (4.5") and least in February (2.4"); May to September bring 46% of it.

The nearest other station, Lebanon Municipal Airport, NH, 8 miles south of Norwich, has a last frost 8 days later (May 9), a first frost 7 days earlier (October 6), a season 14 days shorter.

The first measurable snow (0.1 inch or more) in Norwich usually arrives around November 19, and the last of the season around April 2. Those are the middle dates across the winters of 1991–2020 at Hanover, NH, 2.1 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 29 days after the last snow.

ZIP 05055 is 2 miles from Hanover, NH, which stands at 584 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 03755 (Hanover). The 2023 USDA Plant Hardiness Zone Map lists ZIP 05055 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.