Portola, CA 96135 Frost Dates
96135, near Portola, CA: the frost window
Around 05/22 is the usual last spring frost, about 267 days away. Fall's first freeze usually shows up around 09/25, roughly 122 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Portola in Zone 6b (-5 to 0°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Portola's growing season runs out in roughly 4 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/22 isn't a guarantee
05/22 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/03 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/14 and only about 1 year in 10 sees frost after that.
Portola against the rest of the dataset
About 122 days separate Portola's last and first frost, putting it 38,946 of 40,283 ZIP codes nationally. Within CA, it ranks 2,492 of 2,555.
Learn more
Two guides worth reading on 96135: local microclimates, on what one yard in Portola can differ from the 96135 normal, and zone vs. frost date, on why Zone 6b and Portola's frost date answer different questions.