Frost Dates for 04496 — Winterport, Maine

Half of springs at Bangor International Airport, ME see their last 32°F night by May 4; only one in ten is past it by April 24, and one in ten still has one after May 17. Planting tender crops after May 9 leaves a 30% risk of a frost on them, after May 13 20%, and after May 17 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 October 4 in half of years, as early as September 23 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 13 days later, around October 17; in spring the one-in-ten date for 28°F is May 4, 13 days before the 32°F one. The freeze-free season lasts 152 days in a typical year, longer than at 54% of the 52 Maine stations; it reaches 170 days one year in ten and falls short of 134 one year in ten. On average 161 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 17, and return around September 25. Severe cold of 16°F or below comes every winter, usually between November 24 and March 25.

July is the warmest month at Bangor International Airport, ME, averaging 80°F by day and 59°F at night; January is the coldest at 28°F and 9°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 67% of years.

Warmth for growing adds up to 2,155 growing degree days a year (base 50°F), more than at 71% of the 52 Maine stations. 28% of them (603) have built up by the end of June, and July adds the most, 604. Precipitation totals 41.8 inches a year, most in October (4.6") and least in February (2.4"); May to September bring 41% of it.

The nearest other station, Belfast, ME, 19 miles south of Winterport, has a last frost 3 days later (May 7), a first frost 1 day later (October 5), a season 1 day shorter.

The first measurable snow (0.1 inch or more) in Winterport usually arrives around November 24, and the last of the season around April 6. Those are the middle dates across the winters of 1991–2020 at Bangor International Airport, ME, 10.4 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 28 days after the last snow.

ZIP 04496 is 10 miles from Bangor International Airport, ME, which stands at 148 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 8 other ZIP codes share the station; its figures are presented in full for 04401 (Bangor). The 2023 USDA Plant Hardiness Zone Map lists ZIP 04496 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.