Grass Valley, CA 95949 Frost Dates
Frost dates for Grass Valley, CA, ZIP 95949
Typically, the last spring freeze lands around 04/10, roughly 225 days out. The first fall frost typically arrives around 11/13, about 215 frost-free days later.
The USDA Plant Hardiness Zone Map puts Grass Valley in Zone 9b (25 to 30°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 9b around Grass Valley has about 11 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 04/10 isn't a guarantee
04/10 is the middle of 30 years of NOAA records, not a promise. Plant by 03/17 and you're betting against frost in roughly 9 years out of 10. 04/30 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Grass Valley compares
About 215 days separate Grass Valley's last and first frost, putting it 14,049 of 40,283 ZIP codes nationally. Within CA, it ranks 2,188 of 2,555.
Learn more
the frost range explains how to read the range around Grass Valley's dates instead of trusting one, and local microclimates explains what one yard in Grass Valley can differ from the 95949 normal.