Harrisburg, PA 17120 Frost Dates
Harrisburg, PA: when does the frost end?
Around 04/09 is the usual last spring frost, about 224 days away. 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.
Why 04/09 isn't a guarantee
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
About 205 days separate Harrisburg's last and first frost, putting it 16,167 of 40,283 ZIP codes nationally. Within PA, it ranks 117 of 2,088.
Learn more
Before leaning on 17120's figures: local microclimates explains what one yard in Harrisburg can differ from the 17120 normal, while zone vs. frost date explains why Zone 7a and Harrisburg's frost date answer different questions.