Sonoma, CA 95431 Frost Dates
95431, near Sonoma, CA: the frost window
Around 03/02 is the usual last spring frost, about 186 days away. Fall's first freeze usually shows up around 11/27, roughly 270 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Sonoma 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
Sonoma's growing season runs out in roughly 13 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Sonoma's last frost
03/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 01/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/05 and only about 1 year in 10 sees frost after that.
Sonoma against the rest of the dataset
At roughly 270 frost-free days, Sonoma places 5,562 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,974 of 2,555.
Learn more
Two guides worth reading on 95431: the frost range, on how to read the range around Sonoma's dates instead of trusting one, and local microclimates, on what one yard in Sonoma can differ from the 95431 normal.