Walnut Creek, CA 94598 Frost Dates
94598, near Walnut Creek, CA: the frost window
Typically, the last spring freeze lands around 01/07, roughly 132 days out. Fall's first freeze usually shows up around 12/19, roughly 346 days after the last spring frost.
Walnut Creek 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
Walnut Creek's growing season runs out in roughly 16 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
01/07 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/01 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.
Walnut Creek against the rest of the dataset
At roughly 346 frost-free days, Walnut Creek places 2,421 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,103 of 2,555.
Learn more
Two guides worth reading on 94598: zone vs. frost date, on why Zone 9b and Walnut Creek's frost date answer different questions, and the frost range, on how to read the range around Walnut Creek's dates instead of trusting one.