San Luis Obispo, CA 93408 Frost Dates
93408, near San Luis Obispo, CA: the frost window
Typically, the last spring freeze lands around 01/16, roughly 141 days out. Fall's first freeze usually shows up around 12/25, roughly 349 days after the last spring frost.
San Luis Obispo 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.
Stretching the season past the first frost
San Luis Obispo's growing season runs out in roughly 17 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
01/16 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/26 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/11 and only about 1 year in 10 sees frost after that.
San Luis Obispo against the rest of the dataset
About 349 days separate San Luis Obispo's last and first frost, putting it 2,337 of 40,283 ZIP codes nationally. Within CA, it ranks 1,043 of 2,555.
Learn more
Two guides worth reading on 93408: zone vs. frost date, on why Zone 10a and San Luis Obispo's frost date answer different questions, and the frost range, on how to read the range around San Luis Obispo's dates instead of trusting one.