Atherton, CA 94061 Frost Dates
Atherton, CA: when does the frost end?
Typically, the last spring freeze lands around 01/17, roughly 142 days out. Fall's first freeze usually shows up around 12/12, roughly 333 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 Atherton, not a forecast for this year.
Stretching the season past the first frost
With roughly 15 weeks until Atherton's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 01/17 isn't a guarantee
01/17 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/16 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.
Atherton against the rest of the dataset
At roughly 333 frost-free days, Atherton places 2,847 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,293 of 2,555.
Learn more
Before leaning on 94061's figures: the frost range explains how to read the range around Atherton's dates instead of trusting one, while local microclimates explains what one yard in Atherton can differ from the 94061 normal.