Sonora, CA 95370 Frost Dates
Frost dates for Sonora, CA, ZIP 95370
Typically, the last spring freeze lands around 04/09, roughly 224 days out. The first fall frost typically arrives around 11/09, about 213 frost-free days later.
Sonora sits in USDA Zone 9a (20 to 25°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 9a around Sonora has about 10 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 04/09 isn't a guarantee
04/09 is the middle of 30 years of NOAA records, not a promise. Plant by 03/15 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 Sonora compares
About 213 days separate Sonora's last and first frost, putting it 14,495 of 40,283 ZIP codes nationally. Within CA, it ranks 2,199 of 2,555.
Learn more
local microclimates explains what one yard in Sonora can differ from the 95370 normal, and zone vs. frost date explains why Zone 9a and Sonora's frost date answer different questions.