Williamsport, PA 17728 Frost Dates
17728, near Williamsport, PA: the frost window
Typically, the last spring freeze lands around 04/24, roughly 239 days out. Fall's first freeze usually shows up around 10/23, roughly 180 days after the last spring frost.
Zone 6a (-10 to -5°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Williamsport, not a forecast for this year.
Stretching the season past the first frost
Williamsport'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
04/24 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/12 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/11 and only about 1 year in 10 sees frost after that.
Williamsport against the rest of the dataset
At roughly 180 frost-free days, Williamsport places 24,792 of 40,283 ZIP codes in this dataset. Within PA, it ranks 846 of 2,088.
Learn more
Two guides worth reading on 17728: local microclimates, on what one yard in Williamsport can differ from the 17728 normal, and zone vs. frost date, on why Zone 6a and Williamsport's frost date answer different questions.