Frost Dates for 06514 — Hamden, Connecticut

Half of springs at Mt Carmel, CT see their last 32°F night by April 18; only one in ten is past it by April 5, and one in ten still has one after May 3. Planting tender crops after April 23 leaves a 30% risk of a frost on them, after April 28 20%, and after May 3 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 50% of the 28 Connecticut stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 26 in half of years, as early as October 11 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 11 days later, around November 6; in spring the one-in-ten date for 28°F is April 19, 14 days before the 32°F one. The freeze-free season lasts 191 days in a typical year, longer than at 68% of the 28 Connecticut stations; it reaches 208 days one year in ten and falls short of 172 one year in ten. On average 123 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 1, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 16 and March 7.

July is the warmest month at Mt Carmel, CT, averaging 85°F by day and 64°F at night; January is the coldest at 38°F and 20°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 15% of years.

Warmth for growing adds up to 3,078 growing degree days a year (base 50°F), more than at 79% of the 28 Connecticut stations. 31% of them (949) have built up by the end of June, and July adds the most, 752. Precipitation totals 50.5 inches a year, most in June (4.9") and least in February (3.5"); May to September bring 41% of it.

The nearest other station, New Haven Tweed Airport, CT, 7 miles south of Hamden and 177 feet lower, has a last frost 1 day earlier (April 17), a first frost 1 day later (October 27), a season 2 days longer.

The first measurable snow (0.1 inch or more) in Hamden usually arrives around December 8, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Mt Carmel, CT, 3.9 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 06514 is 4 miles from Mt Carmel, CT, which stands at 180 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 06770 (Naugatuck). The 2023 USDA Plant Hardiness Zone Map lists ZIP 06514 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.