San Fernando, CA 91343 Frost Dates
Frost dates for San Fernando, CA, ZIP 91343
Typically, the last spring freeze lands around 12/31, roughly 125 days out. The first fall frost typically arrives around 12/30, about 365 frost-free days later.
San Fernando sits in USDA Zone 10a (30 to 35°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 10a around San Fernando has about 18 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 12/31 isn't a guarantee
12/31 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. 12/09 is the safer bet, historically only a 1-in-10 chance of frost that late.
How San Fernando compares
At roughly 365 frost-free days, San Fernando places 1,192 of 40,283 ZIP codes in this dataset. Within CA, it ranks 513 of 2,555.
Learn more
local microclimates explains what one yard in San Fernando can differ from the 91343 normal, and zone vs. frost date explains why Zone 10a and San Fernando's frost date answer different questions.