Port Jefferson, NY 11776 Frost Dates
11776, near Port Jefferson, NY: the frost window
Typically, the last spring freeze lands around 04/04, roughly 219 days out. Fall's first freeze usually shows up around 11/07, roughly 215 days after the last spring frost.
Port Jefferson sits in USDA Zone 7b (5 to 10°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
Port Jefferson's growing season runs out in roughly 10 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/04 isn't a guarantee
04/04 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/19 and only about 1 year in 10 sees frost after that.
Port Jefferson against the rest of the dataset
Port Jefferson's growing season runs about 215 days, ranking 14,067 of 40,283 US ZIP codes measured here, longest to shortest. Within NY, it ranks 217 of 1,951.
Learn more
Two guides worth reading on 11776: zone vs. frost date, on why Zone 7b and Port Jefferson's frost date answer different questions, and the frost range, on how to read the range around Port Jefferson's dates instead of trusting one.