Mercersburg, PA 17231 Frost Dates
When can you plant in Mercersburg, PA?
Typically, the last spring freeze lands around 04/07, roughly 222 days out. The first fall frost typically arrives around 11/04, about 209 frost-free days later.
Mercersburg 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 10 weeks of growing season left in Mercersburg before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Mercersburg's last frost
04/07 is the middle of 30 years of NOAA records, not a promise. Plant by 03/25 and you're betting against frost in roughly 9 years out of 10. 04/21 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Mercersburg compares
At roughly 209 frost-free days, Mercersburg places 15,296 of 40,283 ZIP codes in this dataset. Within PA, it ranks 93 of 2,088.
Learn more
zone vs. frost date covers why Zone 7a and Mercersburg's frost date answer different questions. the frost range covers how to read the range around Mercersburg's dates instead of trusting one.