Glendora, CA 91741 Frost Dates
Frost dates for Glendora, CA, ZIP 91741
Typically, the last spring freeze lands around 01/08, roughly 133 days out. The first fall frost typically arrives around 12/28, about 354 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 Glendora, not a forecast for this year.
What to do before the first frost
Zone 10a around Glendora 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 Glendora'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 Glendora compares
At roughly 354 frost-free days, Glendora places 2,170 of 40,283 ZIP codes in this dataset. Within CA, it ranks 974 of 2,555.
Learn more
local microclimates explains what one yard in Glendora can differ from the 91741 normal, and zone vs. frost date explains why Zone 10a and Glendora's frost date answer different questions.