Frost Dates for 06877 — Ridgefield, Connecticut

Half of springs at Danbury Municipal Airport, CT see their last 32°F night by May 1; only one in ten is past it by April 18, and one in ten still has one after May 16. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 10 20%, and after May 16 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 14 in half of years, as early as October 1 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 13 days later, around October 27; in spring the one-in-ten date for 28°F is May 4, 12 days before the 32°F one. The freeze-free season lasts 166 days in a typical year, shorter than at 82% of the 28 Connecticut stations; it reaches 187 days one year in ten and falls short of 146 one year in ten. On average 134 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 12, and return around October 2. Severe cold of 16°F or below comes every winter, usually between December 1 and March 13.

July is the warmest month at Danbury Municipal Airport, CT, averaging 82°F by day and 62°F at night; January is the coldest at 36°F and 18°F. A freezing night is all but certain in every month from October 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 52% of years.

Warmth for growing adds up to 2,690 growing degree days a year (base 50°F), fewer than at 64% of the 28 Connecticut stations. 31% of them (841) have built up by the end of June, and July adds the most, 682. Precipitation totals 48.1 inches a year, most in September (4.8") and least in February (2.7"); May to September bring 46% of it.

The nearest other station, Danbury, CT, 8 miles northeast of Ridgefield, has a last frost 11 days earlier (April 20), a first frost 6 days later (October 20), a season 15 days longer.

The first measurable snow (0.1 inch or more) in Ridgefield usually arrives around November 24, and the last of the season around April 4. Those are the middle dates across the winters of 1991–2020 at Danbury, CT, 8 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 27 days after the last snow.

ZIP 06877 is 5 miles from Danbury Municipal Airport, CT, which stands at 457 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 06877 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.