Fairfield, CA 94585 Frost Dates
94585, near Fairfield, CA: the frost window
Typically, the last spring freeze lands around 01/15, roughly 140 days out. Fall's first freeze usually shows up around 12/14, roughly 336 days after the last spring frost.
Fairfield sits in USDA Zone 9b (25 to 30°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Fairfield's growing season runs out in roughly 15 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
01/15 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/16 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/22 and only about 1 year in 10 sees frost after that.
Fairfield against the rest of the dataset
About 336 days separate Fairfield's last and first frost, putting it 2,708 of 40,283 ZIP codes nationally. Within CA, it ranks 1,231 of 2,555.
Learn more
Two guides worth reading on 94585: local microclimates, on what one yard in Fairfield can differ from the 94585 normal, and zone vs. frost date, on why Zone 9b and Fairfield's frost date answer different questions.