Irwin, PA 15678 Frost Dates
15678, near Irwin, PA: the frost window
Typically, the last spring freeze lands around 05/02, roughly 247 days out. Fall's first freeze usually shows up around 10/20, roughly 170 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Irwin in Zone 6b (-5 to 0°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Irwin's growing season runs out in roughly 8 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
05/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/17 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/20 and only about 1 year in 10 sees frost after that.
Irwin against the rest of the dataset
Irwin's growing season runs about 170 days, ranking 29,011 of 40,283 US ZIP codes measured here, longest to shortest. Within PA, it ranks 1,472 of 2,088.
Learn more
Two guides worth reading on 15678: the frost range, on how to read the range around Irwin's dates instead of trusting one, and local microclimates, on what one yard in Irwin can differ from the 15678 normal.