Oroville, CA 95940 Frost Dates
95940, near Oroville, CA: the frost window
The last spring frost here typically falls around 05/04, about 249 days from today. Fall's first freeze usually shows up around 10/30, roughly 174 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 Oroville, not a forecast for this year.
Stretching the season past the first frost
Oroville's growing season runs out in roughly 9 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
05/04 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/31 and only about 1 year in 10 sees frost after that.
Oroville against the rest of the dataset
About 174 days separate Oroville's last and first frost, putting it 27,370 of 40,283 ZIP codes nationally. Within CA, it ranks 2,365 of 2,555.
Learn more
Two guides worth reading on 95940: local microclimates, on what one yard in Oroville can differ from the 95940 normal, and zone vs. frost date, on why Zone 9b and Oroville's frost date answer different questions.