San Marcos, CA 92078 Frost Dates
Frost dates for San Marcos, CA, ZIP 92078
Around 01/02 is the usual last spring frost, about 127 days away. The first fall frost typically arrives around 12/30, about 365 frost-free days later.
Zone 10a (30 to 35°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for San Marcos, not a forecast for this year.
What to do before the first frost
Zone 10a around San Marcos 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.
The actual range around San Marcos's last frost
01/02 is the middle of 30 years of NOAA records, not a promise. Plant by 02/04 and you're betting against frost in roughly 9 years out of 10. 12/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How San Marcos compares
At roughly 365 frost-free days, San Marcos places 556 of 40,283 ZIP codes in this dataset. Within CA, it ranks 242 of 2,555.
Learn more
local microclimates explains what one yard in San Marcos can differ from the 92078 normal, and zone vs. frost date explains why Zone 10a and San Marcos's frost date answer different questions.