Portola Valley, CA 94020 Frost Dates
When can you plant in Portola Valley, CA?
The last spring frost here typically falls around 03/02, about 186 days from today. The first fall frost typically arrives around 11/25, about 268 frost-free days later.
Portola Valley sits in USDA Zone 9b (25 to 30°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
About 13 weeks of growing season left in Portola Valley before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
03/02 is the middle of 30 years of NOAA records, not a promise. Plant by 04/15 and you're betting against frost in roughly 9 years out of 10. 12/31 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Portola Valley compares
About 268 days separate Portola Valley's last and first frost, putting it 5,762 of 40,283 ZIP codes nationally. Within CA, it ranks 1,986 of 2,555.
Learn more
the frost range covers how to read the range around Portola Valley's dates instead of trusting one. local microclimates covers what one yard in Portola Valley can differ from the 94020 normal.