San Bernardino, CA 92401 Frost Dates
92401, near San Bernardino, CA: the frost window
Around 01/27 is the usual last spring frost, about 152 days away. Fall's first freeze usually shows up around 12/19, roughly 329 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts San Bernardino in Zone 10a (30 to 35°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
San Bernardino'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
01/27 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/28 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/21 and only about 1 year in 10 sees frost after that.
San Bernardino against the rest of the dataset
At roughly 329 frost-free days, San Bernardino places 3,065 of 40,283 ZIP codes in this dataset. Within CA, it ranks 1,318 of 2,555.
Learn more
Two guides worth reading on 92401: local microclimates, on what one yard in San Bernardino can differ from the 92401 normal, and zone vs. frost date, on why Zone 10a and San Bernardino's frost date answer different questions.