La Mesa, CA 91942 Frost Dates
La Mesa, CA: when does the frost end?
Typically, the last spring freeze lands around 01/06, roughly 131 days out. Fall's first freeze usually shows up around 12/21, roughly 350 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 La Mesa, not a forecast for this year.
Stretching the season past the first frost
With roughly 16 weeks until La Mesa'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
01/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/07 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/13 and only about 1 year in 10 sees frost after that.
La Mesa against the rest of the dataset
La Mesa's growing season runs about 350 days, ranking 2,323 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 1,029 of 2,555.
Learn more
Before leaning on 91942's figures: zone vs. frost date explains why Zone 10b and La Mesa's frost date answer different questions, while the frost range explains how to read the range around La Mesa's dates instead of trusting one.