Allentown, PA 18104 Frost Dates
18104, near Allentown, PA: the frost window
Around 04/20 is the usual last spring frost, about 235 days away. Fall's first freeze usually shows up around 10/24, roughly 184 days after the last spring frost.
Allentown 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.
Stretching the season past the first frost
Allentown'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.
The actual range around Allentown's last frost
04/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/06 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.
Allentown against the rest of the dataset
About 184 days separate Allentown's last and first frost, putting it 23,388 of 40,283 ZIP codes nationally. Within PA, it ranks 754 of 2,088.
Learn more
Two guides worth reading on 18104: local microclimates, on what one yard in Allentown can differ from the 18104 normal, and zone vs. frost date, on why Zone 7a and Allentown's frost date answer different questions.