Harrisburg, PA 17105 Frost Dates
Frost dates for Harrisburg, PA, ZIP 17105
The last spring frost here typically falls around 04/09, about 224 days from today. The first fall frost typically arrives around 11/01, about 205 frost-free days later.
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.
What to do before the first frost
Zone 7a around Harrisburg has about 9 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
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
Harrisburg's growing season runs about 205 days, ranking 16,164 of 40,283 US ZIP codes measured here, longest to shortest. Within PA, it ranks 114 of 2,088.
Learn more
the frost range explains how to read the range around Harrisburg's dates instead of trusting one, and local microclimates explains what one yard in Harrisburg can differ from the 17105 normal.