Newtown, CT 06857 Frost Dates
06857, near Newtown, CT: the frost window
Typically, the last spring freeze lands around 04/20, roughly 235 days out. Fall's first freeze usually shows up around 10/20, roughly 181 days after the last spring frost.
Newtown sits in USDA Zone 7a (0 to 5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Newtown's growing season runs out in roughly 8 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/20 isn't a guarantee
04/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/07 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/06 and only about 1 year in 10 sees frost after that.
Newtown against the rest of the dataset
Newtown's growing season runs about 181 days, ranking 24,586 of 40,283 US ZIP codes measured here, longest to shortest. Within CT, it ranks 261 of 391.
Learn more
Two guides worth reading on 06857: local microclimates, on what one yard in Newtown can differ from the 06857 normal, and zone vs. frost date, on why Zone 7a and Newtown's frost date answer different questions.