Frost Dates for 04841 — Rockland, Maine

Half of springs at W Rockport 1 NNW, ME see their last 32°F night by April 27; only one in ten is past it by April 17, and one in ten still has one after May 9. Planting tender crops after May 1 leaves a 30% risk of a frost on them, after May 4 20%, and after May 9 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 67% of the 52 Maine stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 19 in half of years, as early as October 5 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 12 days later, around October 31; in spring the one-in-ten date for 28°F is April 26, 13 days before the 32°F one. The freeze-free season lasts 175 days in a typical year, longer than at 92% of the 52 Maine stations; it reaches 192 days one year in ten and falls short of 156 one year in ten. On average 148 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 11 days longer, to about May 8, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 1 and March 21.

July is the warmest month at W Rockport 1 NNW, ME, averaging 77°F by day and 60°F at night; January is the coldest at 30°F and 12°F. A freezing night is all but certain in every month from November 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 33% of years.

Warmth for growing adds up to 2,043 growing degree days a year (base 50°F), more than at 54% of the 52 Maine stations. 26% of them (529) have built up by the end of June, and July adds the most, 563. Precipitation totals 56.3 inches a year, most in October (6.1") and least in July (3.2"); May to September bring 35% of it.

The nearest other station, Tenants Harbor, ME, 10 miles southwest of Rockland and 340 feet lower, has the same 50% last-frost date, a first frost 6 days later (October 25), a season 3 days longer.

The first measurable snow (0.1 inch or more) in Rockland usually arrives around December 3, and the last of the season around April 2. Those are the middle dates across the winters of 1991–2020 at W Rockport 1 NNW, ME, 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 25 days after the last snow.

ZIP 04841 is 6 miles from W Rockport 1 NNW, ME, which stands at 361 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 04841 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.