San Mateo, CA 94402 Frost Dates
Frost dates for San Mateo, CA, ZIP 94402
The last spring frost here typically falls around 12/29, about 123 days from today. The first fall frost typically arrives around 12/26, 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 Mateo, not a forecast for this year.
What to do before the first frost
Zone 10a around San Mateo has about 17 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 Mateo's last frost
12/29 is the middle of 30 years of NOAA records, not a promise. Plant by 01/13 and you're betting against frost in roughly 9 years out of 10. 12/11 is the safer bet, historically only a 1-in-10 chance of frost that late.
How San Mateo compares
San Mateo's growing season runs about 365 days, ranking 496 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 212 of 2,555.
Learn more
the frost range explains how to read the range around San Mateo's dates instead of trusting one, and local microclimates explains what one yard in San Mateo can differ from the 94402 normal.