Riverside, CA 92503 Frost Dates
When can you plant in Riverside, CA?
The last spring frost here typically falls around 01/09, about 134 days from today. The first fall frost typically arrives around 12/30, about 362 frost-free days later.
Riverside 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.
What to do before the first frost
About 18 weeks of growing season left in Riverside 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
01/09 is the middle of 30 years of NOAA records, not a promise. Plant by 02/21 and you're betting against frost in roughly 9 years out of 10. 12/16 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Riverside compares
Riverside's growing season runs about 362 days, ranking 2,056 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 942 of 2,555.
Learn more
local microclimates covers what one yard in Riverside can differ from the 92503 normal. zone vs. frost date covers why Zone 10a and Riverside's frost date answer different questions.