El Cajon, CA 91948 Frost Dates
Frost dates for El Cajon, CA, ZIP 91948
Around 04/19 is the usual last spring frost, about 234 days away. The first fall frost typically arrives around 10/27, about 190 frost-free days later.
Zone 8a (10 to 15°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 El Cajon, not a forecast for this year.
What to do before the first frost
Zone 8a around El Cajon has about 9 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 04/19 isn't a guarantee
04/19 is the middle of 30 years of NOAA records, not a promise. Plant by 03/24 and you're betting against frost in roughly 9 years out of 10. 05/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How El Cajon compares
At roughly 190 frost-free days, El Cajon places 20,980 of 40,283 ZIP codes in this dataset. Within CA, it ranks 2,313 of 2,555.
Learn more
zone vs. frost date explains why Zone 8a and El Cajon's frost date answer different questions, and the frost range explains how to read the range around El Cajon's dates instead of trusting one.