Williamsport, PA 17723 Frost Dates
When can you plant in Williamsport, PA?
Typically, the last spring freeze lands around 04/24, roughly 239 days out. The first fall frost typically arrives around 10/23, about 180 frost-free days later.
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.
What to do before the first frost
About 8 weeks of growing season left in Williamsport before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/24 isn't a guarantee
04/24 is the middle of 30 years of NOAA records, not a promise. Plant by 04/12 and you're betting against frost in roughly 9 years out of 10. 05/11 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Williamsport compares
Williamsport's growing season runs about 180 days, ranking 24,790 of 40,283 US ZIP codes measured here, longest to shortest. Within PA, it ranks 844 of 2,088.
Learn more
local microclimates covers what one yard in Williamsport can differ from the 17723 normal. zone vs. frost date covers why Zone 6a and Williamsport's frost date answer different questions.