El Cajon, CA 92021 Frost Dates
El Cajon, CA: when does the frost end?
Typically, the last spring freeze lands around 01/06, roughly 131 days out. Fall's first freeze usually shows up around 12/21, roughly 350 days after the last spring frost.
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 El Cajon, not a forecast for this year.
Stretching the season past the first frost
With roughly 16 weeks until El Cajon's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 01/06 isn't a guarantee
01/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/07 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/13 and only about 1 year in 10 sees frost after that.
El Cajon against the rest of the dataset
At roughly 350 frost-free days, El Cajon places 2,320 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,026 of 2,555.
Learn more
Before leaning on 92021's figures: zone vs. frost date explains why Zone 10a and El Cajon's frost date answer different questions, while the frost range explains how to read the range around El Cajon's dates instead of trusting one.