Norwalk, CT 06840 Frost Dates
06840, near Norwalk, CT: the frost window
Typically, the last spring freeze lands around 04/17, roughly 232 days out. Fall's first freeze usually shows up around 10/23, roughly 188 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Norwalk in Zone 7a (0 to 5°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Norwalk'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.
How much risk comes with planting early here
04/17 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/03 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/02 and only about 1 year in 10 sees frost after that.
Norwalk against the rest of the dataset
Norwalk's growing season runs about 188 days, ranking 21,807 of 40,283 US ZIP codes measured here, longest to shortest. Within CT, it ranks 218 of 391.
Learn more
Two guides worth reading on 06840: zone vs. frost date, on why Zone 7a and Norwalk's frost date answer different questions, and the frost range, on how to read the range around Norwalk's dates instead of trusting one.