Riverside, CA 92506 Frost Dates
92506, near Riverside, CA: the frost window
The last spring frost here typically falls around 01/09, about 134 days from today. Fall's first freeze usually shows up around 12/25, roughly 353 days after the last spring frost.
Zone 10a (30 to 35°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 Riverside, not a forecast for this year.
Stretching the season past the first frost
Riverside's growing season runs out in roughly 17 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 01/09 isn't a guarantee
01/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/25 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/16 and only about 1 year in 10 sees frost after that.
Riverside against the rest of the dataset
Riverside's growing season runs about 353 days, ranking 2,202 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 986 of 2,555.
Learn more
Two guides worth reading on 92506: the frost range, on how to read the range around Riverside's dates instead of trusting one, and local microclimates, on what one yard in Riverside can differ from the 92506 normal.