Mercersburg, PA 17252 Frost Dates
17252, near Mercersburg, PA: the frost window
Typically, the last spring freeze lands around 04/07, roughly 222 days out. Fall's first freeze usually shows up around 11/04, roughly 209 days after the last spring frost.
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 Mercersburg, not a forecast for this year.
Stretching the season past the first frost
Mercersburg's growing season runs out in roughly 10 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
04/07 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/25 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/21 and only about 1 year in 10 sees frost after that.
Mercersburg against the rest of the dataset
About 209 days separate Mercersburg's last and first frost, putting it 15,298 of 40,283 ZIP codes nationally. Within PA, it ranks 95 of 2,088.
Learn more
Two guides worth reading on 17252: zone vs. frost date, on why Zone 7a and Mercersburg's frost date answer different questions, and the frost range, on how to read the range around Mercersburg's dates instead of trusting one.