Windsor, CA 95439 Frost Dates
Frost dates for Windsor, CA, ZIP 95439
Around 03/02 is the usual last spring frost, about 186 days away. The first fall frost typically arrives around 11/20, about 262 frost-free days later.
The USDA Plant Hardiness Zone Map puts Windsor in Zone 9a (20 to 25°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 9a around Windsor has about 12 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 03/02 isn't a guarantee
03/02 is the middle of 30 years of NOAA records, not a promise. Plant by 01/27 and you're betting against frost in roughly 9 years out of 10. 04/02 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Windsor compares
At roughly 262 frost-free days, Windsor places 6,203 of 40,283 ZIP codes in this dataset. Within CA, it ranks 2,025 of 2,555.
Learn more
the frost range explains how to read the range around Windsor's dates instead of trusting one, and local microclimates explains what one yard in Windsor can differ from the 95439 normal.