Castle Shannon, PA 15228 Frost Dates
15228, near Castle Shannon, PA: the frost window
The last spring frost here typically falls around 04/18, about 233 days from today. Fall's first freeze usually shows up around 10/28, roughly 193 days after the last spring frost.
Castle Shannon sits in USDA Zone 6b (-5 to 0°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
Castle Shannon's growing season runs out in roughly 9 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
04/18 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/02 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/06 and only about 1 year in 10 sees frost after that.
Castle Shannon against the rest of the dataset
Castle Shannon's growing season runs about 193 days, ranking 19,824 of 40,283 US ZIP codes measured here, longest to shortest. Within PA, it ranks 420 of 2,088.
Learn more
Two guides worth reading on 15228: zone vs. frost date, on why Zone 6b and Castle Shannon's frost date answer different questions, and the frost range, on how to read the range around Castle Shannon's dates instead of trusting one.