San Dimas, CA 91773 Frost Dates
Frost dates for San Dimas, CA, ZIP 91773
The last spring frost here typically falls around 01/08, about 133 days from today. The first fall frost typically arrives around 12/28, about 354 frost-free days later.
The USDA Plant Hardiness Zone Map puts San Dimas in Zone 10a (30 to 35°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 10a around San Dimas 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.
The actual range around San Dimas's last frost
01/08 is the middle of 30 years of NOAA records, not a promise. Plant by 02/18 and you're betting against frost in roughly 9 years out of 10. 12/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How San Dimas compares
San Dimas's growing season runs about 354 days, ranking 2,183 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 981 of 2,555.
Learn more
local microclimates explains what one yard in San Dimas can differ from the 91773 normal, and zone vs. frost date explains why Zone 10a and San Dimas's frost date answer different questions.