Napa, CA 94559 Frost Dates
Frost dates for Napa, CA, ZIP 94559
Typically, the last spring freeze lands around 02/12, roughly 168 days out. The first fall frost typically arrives around 12/04, about 299 frost-free days later.
Napa sits in USDA Zone 9b (25 to 30°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 9b around Napa has about 14 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.
The actual range around Napa's last frost
02/12 is the middle of 30 years of NOAA records, not a promise. Plant by 01/03 and you're betting against frost in roughly 9 years out of 10. 03/13 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Napa compares
Napa's growing season runs about 299 days, ranking 4,153 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 1,640 of 2,555.
Learn more
the frost range explains how to read the range around Napa's dates instead of trusting one, and local microclimates explains what one yard in Napa can differ from the 94559 normal.