Herndon, VA 20191 Frost Dates
Frost dates for Herndon, VA, ZIP 20191
Around 04/14 is the usual last spring frost, about 229 days away. The first fall frost typically arrives around 10/29, about 198 frost-free days later.
Herndon sits in USDA Zone 7b (5 to 10°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
Zone 7b around Herndon has about 9 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 04/14 isn't a guarantee
04/14 is the middle of 30 years of NOAA records, not a promise. Plant by 03/30 and you're betting against frost in roughly 9 years out of 10. 04/28 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Herndon compares
At roughly 198 frost-free days, Herndon places 18,349 of 40,283 ZIP codes in this dataset. Within VA, it ranks 688 of 1,178.
Learn more
the frost range explains how to read the range around Herndon's dates instead of trusting one, and local microclimates explains what one yard in Herndon can differ from the 20191 normal.