San Luis Obispo, CA 93409 Frost Dates
When can you plant in San Luis Obispo, CA?
The last spring frost here typically falls around 01/31, about 156 days from today. 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
At roughly 319 frost-free days, San Luis Obispo places 3,317 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,401 of 2,555.
Learn more
local microclimates covers what one yard in San Luis Obispo can differ from the 93409 normal. zone vs. frost date covers why Zone 9b and San Luis Obispo's frost date answer different questions.