Philadelphia, PA 19173 Frost Dates
Philadelphia, PA: when does the frost end?
Typically, the last spring freeze lands around 04/15, roughly 230 days out. Fall's first freeze usually shows up around 10/31, roughly 199 days after the last spring frost.
Philadelphia sits in USDA Zone 7b (5 to 10°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.
Stretching the season past the first frost
With roughly 9 weeks until Philadelphia'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
04/15 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/01 and only about 1 year in 10 sees frost after that.
Philadelphia against the rest of the dataset
At roughly 199 frost-free days, Philadelphia places 17,949 of 40,283 ZIP codes in this dataset. Within PA, it ranks 262 of 2,088.
Learn more
Before leaning on 19173's figures: zone vs. frost date explains why Zone 7b and Philadelphia's frost date answer different questions, while the frost range explains how to read the range around Philadelphia's dates instead of trusting one.