San Mateo, CA 94403 Frost Dates
San Mateo, CA: when does the frost end?
The last spring frost here typically falls around 01/17, about 142 days from today. Fall's first freeze usually shows up around 12/12, roughly 333 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts San Mateo in Zone 10a (30 to 35°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 15 weeks until San Mateo's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
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.
San Mateo against the rest of the dataset
At roughly 333 frost-free days, San Mateo places 2,815 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,280 of 2,555.
Learn more
Before leaning on 94403's figures: the frost range explains how to read the range around San Mateo's dates instead of trusting one, while local microclimates explains what one yard in San Mateo can differ from the 94403 normal.