Philadelphia, PA 19170 Frost Dates
Frost dates for Philadelphia, PA, ZIP 19170
Around 04/15 is the usual last spring frost, about 230 days away. The first fall frost typically arrives around 10/31, about 199 frost-free days later.
Zone 7b (5 to 10°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 Philadelphia, not a forecast for this year.
What to do before the first frost
Zone 7b around Philadelphia 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.
The actual range around Philadelphia's last frost
04/15 is the middle of 30 years of NOAA records, not a promise. Plant by 04/01 and you're betting against frost in roughly 9 years out of 10. 05/01 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Philadelphia compares
About 199 days separate Philadelphia's last and first frost, putting it 17,947 of 40,283 ZIP codes nationally. Within PA, it ranks 260 of 2,088.
Learn more
the frost range explains how to read the range around Philadelphia's dates instead of trusting one, and local microclimates explains what one yard in Philadelphia can differ from the 19170 normal.