Vallejo, CA 94591 Frost Dates
94591, near Vallejo, CA: the frost window
The last spring frost here typically falls around 02/28, about 184 days from today. Fall's first freeze usually shows up around 11/22, roughly 266 days after the last spring frost.
Zone 9b (25 to 30°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Vallejo, not a forecast for this year.
Stretching the season past the first frost
Vallejo's growing season runs out in roughly 12 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
02/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 01/29 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.
Vallejo against the rest of the dataset
At roughly 266 frost-free days, Vallejo places 5,912 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,990 of 2,555.
Learn more
Two guides worth reading on 94591: local microclimates, on what one yard in Vallejo can differ from the 94591 normal, and zone vs. frost date, on why Zone 9b and Vallejo's frost date answer different questions.