Rancho Cucamonga, CA 91730 Frost Dates
Frost dates for Rancho Cucamonga, CA, ZIP 91730
The last spring frost here typically falls around 01/04, about 129 days from today. The first fall frost typically arrives around 12/30, 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 Rancho Cucamonga, not a forecast for this year.
What to do before the first frost
Zone 10a around Rancho Cucamonga has about 18 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.
Why 01/04 isn't a guarantee
01/04 is the middle of 30 years of NOAA records, not a promise. Plant by 02/07 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 Rancho Cucamonga compares
About 365 days separate Rancho Cucamonga's last and first frost, putting it 377 of 40,283 ZIP codes nationally. Within CA, it ranks 131 of 2,555.
Learn more
the frost range explains how to read the range around Rancho Cucamonga's dates instead of trusting one, and local microclimates explains what one yard in Rancho Cucamonga can differ from the 91730 normal.