Palo Alto, CA 94306 Frost Dates
94306, near Palo Alto, CA: the frost window
Around 02/01 is the usual last spring frost, about 157 days away. Fall's first freeze usually shows up around 12/07, roughly 310 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Palo Alto in Zone 9b (25 to 30°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
Palo Alto's growing season runs out in roughly 14 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 02/01 isn't a guarantee
02/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/04 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/28 and only about 1 year in 10 sees frost after that.
Palo Alto against the rest of the dataset
At roughly 310 frost-free days, Palo Alto places 3,551 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,471 of 2,555.
Learn more
Two guides worth reading on 94306: local microclimates, on what one yard in Palo Alto can differ from the 94306 normal, and zone vs. frost date, on why Zone 9b and Palo Alto's frost date answer different questions.