San Luis Obispo, CA 93401 Frost Dates
When can you plant in San Luis Obispo, CA?
Typically, the last spring freeze lands around 01/31, roughly 156 days out. The first fall frost typically arrives around 12/11, about 319 frost-free days later.
Zone 9b (25 to 30°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
About 15 weeks of growing season left in San Luis Obispo before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
01/31 is the middle of 30 years of NOAA records, not a promise. Plant by 03/07 and you're betting against frost in roughly 9 years out of 10. 12/23 is the safer bet, historically only a 1-in-10 chance of frost that late.
How San Luis Obispo compares
San Luis Obispo's growing season runs about 319 days, ranking 3,316 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 1,400 of 2,555.
Learn more
the frost range covers how to read the range around San Luis Obispo's dates instead of trusting one. local microclimates covers what one yard in San Luis Obispo can differ from the 93401 normal.