Frost Dates for 04469 — Orono, Maine

Half of springs at Old Town 2 W, ME see their last 32°F night by May 13; only one in ten is past it by April 30, and one in ten still has one after May 28. Planting tender crops after May 19 leaves a 30% risk of a frost on them, after May 23 20%, and after May 28 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 83% of the 52 Maine stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 28 in half of years, as early as September 16 one year in ten, and holds off past October 11 one year in ten. A hard freeze of 28°F follows 13 days later, around October 11; in spring the one-in-ten date for 28°F is May 13, 15 days before the 32°F one. The freeze-free season lasts 137 days in a typical year, shorter than at 81% of the 52 Maine stations; it reaches 155 days one year in ten and falls short of 117 one year in ten. On average 173 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 15 days longer, to about May 28, and return around September 18. Severe cold of 16°F or below comes every winter, usually between November 20 and March 31.

July is the warmest month at Old Town 2 W, ME, averaging 79°F by day and 56°F at night; January is the coldest at 27°F and 6°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 87% of years.

Warmth for growing adds up to 1,816 growing degree days a year (base 50°F), fewer than at 83% of the 52 Maine stations. 27% of them (486) have built up by the end of June, and July adds the most, 542. Precipitation totals 44.8 inches a year, most in October (4.3") and least in February (3.0"); May to September bring 40% of it.

The nearest other station, Orono, ME, 7 miles south of Orono, has a last frost 12 days earlier (May 1), a first frost 8 days later (October 6), a season 20 days longer.

The first measurable snow (0.1 inch or more) in Orono 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, 16.8 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 37 days after the last snow.

ZIP 04469 is 6 miles from Old Town 2 W, ME, which stands at 127 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 04468 (Old Town). The 2023 USDA Plant Hardiness Zone Map lists ZIP 04469 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.