San Luis Obispo, CA 93403 Frost Dates
Frost dates for San Luis Obispo, CA, ZIP 93403
The last spring frost here typically falls around 01/16, about 141 days from today. The first fall frost typically arrives around 12/25, about 349 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 Luis Obispo, not a forecast for this year.
What to do before the first frost
Zone 10a around San Luis Obispo 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.
Why 01/16 isn't a guarantee
01/16 is the middle of 30 years of NOAA records, not a promise. Plant by 02/26 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 Luis Obispo compares
At roughly 349 frost-free days, San Luis Obispo places 2,333 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,039 of 2,555.
Learn more
zone vs. frost date explains why Zone 10a and San Luis Obispo's frost date answer different questions, and the frost range explains how to read the range around San Luis Obispo's dates instead of trusting one.