Harrisburg, PA 17102 Frost Dates
Harrisburg, PA: when does the frost end?
Typically, the last spring freeze lands around 04/09, roughly 224 days out. Fall's first freeze usually shows up around 11/01, roughly 205 days after the last spring frost.
Zone 7a (0 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 Harrisburg, not a forecast for this year.
Stretching the season past the first frost
With roughly 9 weeks until Harrisburg's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
04/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/25 and only about 1 year in 10 sees frost after that.
Harrisburg against the rest of the dataset
At roughly 205 frost-free days, Harrisburg places 16,163 of 40,283 ZIP codes in this dataset. Within PA, it ranks 113 of 2,088.
Learn more
Before leaning on 17102's figures: zone vs. frost date explains why Zone 7a and Harrisburg's frost date answer different questions, while the frost range explains how to read the range around Harrisburg's dates instead of trusting one.