Rio Vista, CA 94512 Frost Dates
94512, near Rio Vista, CA: the frost window
Typically, the last spring freeze lands around 01/12, roughly 137 days out. Fall's first freeze usually shows up around 12/19, roughly 343 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 Rio Vista, not a forecast for this year.
Stretching the season past the first frost
Rio Vista's growing season runs out in roughly 16 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 01/12 isn't a guarantee
01/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/20 and only about 1 year in 10 sees frost after that.
Rio Vista against the rest of the dataset
About 343 days separate Rio Vista's last and first frost, putting it 2,534 of 40,283 ZIP codes nationally. Within CA, it ranks 1,117 of 2,555.
Learn more
Two guides worth reading on 94512: the frost range, on how to read the range around Rio Vista's dates instead of trusting one, and local microclimates, on what one yard in Rio Vista can differ from the 94512 normal.