Frost Dates for 04027 — Lebanon, Maine

Half of springs at Sanford 2 NNW, ME see their last 32°F night by May 16; only one in ten is past it by May 2, and one in ten still has one after May 29. Planting tender crops after May 21 leaves a 30% risk of a frost on them, after May 24 20%, and after May 29 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 33% of the 52 Maine stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 30 in half of years, as early as September 18 one year in ten, and holds off past October 10 one year in ten. A hard freeze of 28°F follows 7 days later, around October 7; in spring the one-in-ten date for 28°F is May 17, 12 days before the 32°F one. The freeze-free season lasts 136 days in a typical year, shorter than at 83% of the 52 Maine stations; it reaches 153 days one year in ten and falls short of 118 one year in ten. On average 156 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 May 26, and return around September 20. Severe cold of 16°F or below comes every winter, usually between November 16 and March 29.

July is the warmest month at Sanford 2 NNW, ME, averaging 81°F by day and 56°F at night; January is the coldest at 32°F and 10°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 2,120 growing degree days a year (base 50°F), more than at 65% of the 52 Maine stations. 29% of them (616) have built up by the end of June, and July adds the most, 580. Precipitation totals 51.4 inches a year, most in October (5.4") and least in February (3.6"); May to September bring 39% of it.

The nearest other station, Rochester Skyhaven Airport, NH, 9 miles south of Lebanon, has a last frost 16 days earlier (April 30), a first frost 9 days later (October 9), a season 25 days longer.

The first measurable snow (0.1 inch or more) in Lebanon usually arrives around December 4, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Sanford 2 NNW, ME, 7.8 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 53 days after the last snow.

ZIP 04027 is 8 miles from Sanford 2 NNW, ME, which stands at 289 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 04073 (Sanford). The 2023 USDA Plant Hardiness Zone Map lists ZIP 04027 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.