San Marcos, CA 92069 Frost Dates
When can you plant in San Marcos, CA?
Typically, the last spring freeze lands around 01/02, roughly 127 days out. The first fall frost typically arrives around 12/30, about 365 frost-free days later.
San Marcos 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
About 18 weeks of growing season left in San Marcos before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 01/02 isn't a guarantee
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
San Marcos's growing season runs about 365 days, ranking 555 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 241 of 2,555.
Learn more
zone vs. frost date covers why Zone 10a and San Marcos's frost date answer different questions. the frost range covers how to read the range around San Marcos's dates instead of trusting one.