Harrisburg, PA 17121 Frost Dates
When can you plant in Harrisburg, PA?
Around 04/09 is the usual last spring frost, about 224 days away. The first fall frost typically arrives around 11/01, about 205 frost-free days later.
Harrisburg sits in USDA Zone 7a (0 to 5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
About 9 weeks of growing season left in Harrisburg before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
04/09 is the middle of 30 years of NOAA records, not a promise. Plant by 03/27 and you're betting against frost in roughly 9 years out of 10. 04/25 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Harrisburg compares
At roughly 205 frost-free days, Harrisburg places 16,168 of 40,283 ZIP codes in this dataset. Within PA, it ranks 118 of 2,088.
Learn more
local microclimates covers what one yard in Harrisburg can differ from the 17121 normal. zone vs. frost date covers why Zone 7a and Harrisburg's frost date answer different questions.