Herndon, PA 17830 Frost Dates
When can you plant in Herndon, PA?
Typically, the last spring freeze lands around 04/27, roughly 242 days out. The first fall frost typically arrives around 10/16, about 172 frost-free days later.
Herndon 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.
What to do before the first frost
About 7 weeks of growing season left in Herndon before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
04/27 is the middle of 30 years of NOAA records, not a promise. Plant by 04/13 and you're betting against frost in roughly 9 years out of 10. 05/12 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Herndon compares
About 172 days separate Herndon's last and first frost, putting it 28,473 of 40,283 ZIP codes nationally. Within PA, it ranks 1,407 of 2,088.
Learn more
the frost range covers how to read the range around Herndon's dates instead of trusting one. local microclimates covers what one yard in Herndon can differ from the 17830 normal.