Portola, CA 96113 Frost Dates
96113, near Portola, CA: the frost window
Around 05/21 is the usual last spring frost, about 266 days away. Fall's first freeze usually shows up around 10/01, roughly 130 days after the last spring frost.
Portola sits in USDA Zone 7a (0 to 5°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
Portola's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/21 isn't a guarantee
05/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/11 and only about 1 year in 10 sees frost after that.
Portola against the rest of the dataset
At roughly 130 frost-free days, Portola places 38,382 of 40,283 ZIP codes in this dataset. Within CA, it ranks 2,471 of 2,555.
Learn more
Two guides worth reading on 96113: zone vs. frost date, on why Zone 7a and Portola's frost date answer different questions, and the frost range, on how to read the range around Portola's dates instead of trusting one.