Hercules, CA 94547 Frost Dates
When can you plant in Hercules, CA?
Typically, the last spring freeze lands around 02/28, roughly 184 days out. The first fall frost typically arrives around 11/22, about 266 frost-free days later.
The USDA Plant Hardiness Zone Map puts Hercules in Zone 9b (25 to 30°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
About 12 weeks of growing season left in Hercules before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
02/28 is the middle of 30 years of NOAA records, not a promise. Plant by 01/29 and you're betting against frost in roughly 9 years out of 10. 04/05 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Hercules compares
Hercules's growing season runs about 266 days, ranking 5,920 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 1,992 of 2,555.
Learn more
local microclimates covers what one yard in Hercules can differ from the 94547 normal. zone vs. frost date covers why Zone 9b and Hercules's frost date answer different questions.