Fontana, CA 92336 Frost Dates
Frost dates for Fontana, CA, ZIP 92336
Typically, the last spring freeze lands around 01/04, roughly 129 days out. 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 Fontana, not a forecast for this year.
What to do before the first frost
Zone 10a around Fontana 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 Fontana compares
Fontana's growing season runs about 365 days, ranking 349 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 112 of 2,555.
Learn more
zone vs. frost date explains why Zone 10a and Fontana's frost date answer different questions, and the frost range explains how to read the range around Fontana's dates instead of trusting one.