Walnut, CA 91789 Frost Dates
Walnut, CA: when does the frost end?
Typically, the last spring freeze lands around 01/08, roughly 133 days out. Fall's first freeze usually shows up around 12/28, roughly 354 days after the last spring frost.
Walnut sits in USDA Zone 10a (30 to 35°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
With roughly 17 weeks until Walnut's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
01/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/14 and only about 1 year in 10 sees frost after that.
Walnut against the rest of the dataset
Walnut's growing season runs about 354 days, ranking 2,185 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 983 of 2,555.
Learn more
Before leaning on 91789's figures: the frost range explains how to read the range around Walnut's dates instead of trusting one, while local microclimates explains what one yard in Walnut can differ from the 91789 normal.