Frost Dates for 06074 — South Windsor, Connecticut

Half of springs at Hartford Brainard Field, CT see their last 32°F night by April 17; only one in ten is past it by April 1, and one in ten still has one after May 1. Planting tender crops after April 23 leaves a 30% risk of a frost on them, after April 27 20%, and after May 1 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 54% 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 12 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 10 days later, around November 5; in spring the one-in-ten date for 28°F is April 21, 10 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 212 days one year in ten and falls short of 169 one year in ten. On average 121 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 April 30, and return around October 14. Severe cold of 16°F or below comes every winter, usually between December 12 and March 5.

July is the warmest month at Hartford Brainard Field, CT, averaging 85°F by day and 66°F at night; January is the coldest at 37°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 11% of years.

Warmth for growing adds up to 3,238 growing degree days a year (base 50°F), more than at 96% of the 28 Connecticut stations. 32% of them (1,042) have built up by the end of June, and July adds the most, 780. Precipitation totals 42.9 inches a year, most in October (4.2") and least in February (2.6"); May to September bring 44% of it.

The nearest other station, Hartford Bradley International Airport, CT, 9 miles northwest of South Windsor and 171 feet higher, has a last frost 4 days later (April 21), a first frost 10 days earlier (October 16), a season 14 days shorter.

The first measurable snow (0.1 inch or more) in South Windsor usually arrives around December 2, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at Hartford Bradley International Airport, CT, 9.4 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 17 days after the last snow.

ZIP 06074 is 8 miles from Hartford Brainard Field, CT, which stands at 19 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 28 other ZIP codes share the station; its figures are presented in full for 06106 (Hartford). The 2023 USDA Plant Hardiness Zone Map lists ZIP 06074 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.