Williamstown, PA 17978 Frost Dates
Williamstown, PA: when does the frost end?
Around 04/27 is the usual last spring frost, about 242 days away. Fall's first freeze usually shows up around 10/20, roughly 172 days after the last spring frost.
Zone 6b (-5 to 0°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 Williamstown, not a forecast for this year.
Stretching the season past the first frost
With roughly 8 weeks until Williamstown's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/27 isn't a guarantee
04/27 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 05/15 and only about 1 year in 10 sees frost after that.
Williamstown against the rest of the dataset
Williamstown's growing season runs about 172 days, ranking 28,387 of 40,283 US ZIP codes measured here, longest to shortest. Within PA, it ranks 1,385 of 2,088.
Learn more
Before leaning on 17978's figures: zone vs. frost date explains why Zone 6b and Williamstown's frost date answer different questions, while the frost range explains how to read the range around Williamstown's dates instead of trusting one.