Downey, CA 90240 Frost Dates
90240, near Downey, CA: the frost window
Typically, the last spring freeze lands around 01/04, roughly 129 days out. Fall's first freeze usually shows up around 01/02, roughly 365 days after the last spring frost.
Zone 10b (35 to 40°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 Downey, not a forecast for this year.
Stretching the season past the first frost
Downey's growing season runs out in roughly 18 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Downey's last frost
01/04 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 01/28 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/19 and only about 1 year in 10 sees frost after that.
Downey against the rest of the dataset
At roughly 365 frost-free days, Downey places 468 of 40,283 ZIP codes in this dataset. Within CA, it ranks 191 of 2,555.
Learn more
Two guides worth reading on 90240: local microclimates, on what one yard in Downey can differ from the 90240 normal, and zone vs. frost date, on why Zone 10b and Downey's frost date answer different questions.