West Mifflin, PA 15122 Frost Dates
15122, near West Mifflin, PA: the frost window
Around 04/18 is the usual last spring frost, about 233 days away. Fall's first freeze usually shows up around 10/28, roughly 193 days after the last spring frost.
West Mifflin 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
West Mifflin'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.
Why 04/18 isn't a guarantee
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.
West Mifflin against the rest of the dataset
At roughly 193 frost-free days, West Mifflin places 19,748 of 40,283 ZIP codes in this dataset. Within PA, it ranks 412 of 2,088.
Learn more
Two guides worth reading on 15122: zone vs. frost date, on why Zone 6b and West Mifflin's frost date answer different questions, and the frost range, on how to read the range around West Mifflin's dates instead of trusting one.