Frost Dates for 04530 — Bath, Maine

Half of springs at Bath, ME see their last 32°F night by May 10; only one in ten is past it by April 28, and one in ten still has one after May 23. Planting tender crops after May 16 leaves a 30% risk of a frost on them, after May 19 20%, and after May 23 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 6 in half of years, as early as September 25 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 19; in spring the one-in-ten date for 28°F is May 10, 13 days before the 32°F one. The freeze-free season lasts 149 days in a typical year, shorter than at 54% of the 52 Maine stations; it reaches 167 days one year in ten and falls short of 131 one year in ten. On average 162 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 12 days longer, to about May 22, and return around September 26. Severe cold of 16°F or below comes every winter, usually between November 25 and March 24.

July is the warmest month at Bath, ME, averaging 79°F by day and 57°F at night; January is the coldest at 31°F and 10°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 83% of years.

Warmth for growing adds up to 1,918 growing degree days a year (base 50°F), fewer than at 65% of the 52 Maine stations. 25% of them (477) have built up by the end of June, and July adds the most, 558. Precipitation totals 48.5 inches a year, most in October (5.3") and least in July (3.1"); May to September bring 38% of it.

The nearest other station, Brunswick NAS, ME, 5 miles west of Bath, has a last frost 8 days earlier (May 2), a first frost 4 days later (October 10), a season 11 days longer.

The first measurable snow (0.1 inch or more) in Bath usually arrives around November 24, and the last of the season around April 8. Those are the middle dates across the winters of 1991–2020 at Bath, ME, 2.4 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 32 days after the last snow.

ZIP 04530 is 2 miles from Bath, ME, which stands at 25 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 04530 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.