Frost Dates for 04736 — Caribou, Maine

Half of springs at Caribou Municipal Airport, ME see their last 32°F night by May 7; only one in ten is past it by April 27, and one in ten still has one after May 24. Planting tender crops after May 13 leaves a 30% risk of a frost on them, after May 17 20%, and after May 24 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 98% of the 52 Maine stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 1 in half of years, as early as September 17 one year in ten, and holds off past October 14 one year in ten. A hard freeze of 28°F follows 11 days later, around October 12; in spring the one-in-ten date for 28°F is May 7, 17 days before the 32°F one. The freeze-free season lasts 143 days in a typical year, shorter than at 69% of the 52 Maine stations; it reaches 160 days one year in ten and falls short of 124 one year in ten. On average 180 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 17 days longer, to about May 24, and return around September 19. Severe cold of 16°F or below comes every winter, usually between November 16 and April 3.

July is the warmest month at Caribou Municipal Airport, ME, averaging 77°F by day and 56°F at night; January is the coldest at 21°F and 3°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 75% of years.

Warmth for growing adds up to 1,726 growing degree days a year (base 50°F), fewer than at 90% of the 52 Maine stations. 28% of them (485) have built up by the end of June, and July adds the most, 518. Precipitation totals 40.8 inches a year, most in July (4.2") and least in February (2.4"); May to September bring 46% of it.

The nearest other station, Presque Isle, ME, 16 miles south of Caribou, has a last frost 7 days later (May 14), a first frost 5 days earlier (September 26), a season 12 days shorter.

The first measurable snow (0.1 inch or more) in Caribou usually arrives around October 30, and the last of the season around April 24. Those are the middle dates across the winters of 1991–2020 at Caribou Municipal Airport, ME, 0.6 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 13 days after the last snow.

ZIP 04736 is under a mile from Caribou Municipal Airport, ME, which stands at 624 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 04736 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.