Millbrae, CA 94030 Frost Dates
Frost dates for Millbrae, CA, ZIP 94030
Typically, the last spring freeze lands around 12/29, roughly 123 days out. The first fall frost typically arrives around 12/26, about 365 frost-free days later.
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 Millbrae, not a forecast for this year.
What to do before the first frost
Zone 10a around Millbrae has about 17 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
12/29 is the middle of 30 years of NOAA records, not a promise. Plant by 01/13 and you're betting against frost in roughly 9 years out of 10. 12/11 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Millbrae compares
About 365 days separate Millbrae's last and first frost, putting it 1,200 of 40,283 ZIP codes nationally. Within CA, it ranks 519 of 2,555.
Learn more
local microclimates explains what one yard in Millbrae can differ from the 94030 normal, and zone vs. frost date explains why Zone 10a and Millbrae's frost date answer different questions.