Union City, CA 94536 Frost Dates
When can you plant in Union City, CA?
The last spring frost here typically falls around 01/07, about 132 days from today. The first fall frost typically arrives around 12/22, about 353 frost-free days later.
Union City sits in USDA Zone 9b (25 to 30°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 17 weeks of growing season left in Union City before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Union City's last frost
01/07 is the middle of 30 years of NOAA records, not a promise. Plant by 02/07 and you're betting against frost in roughly 9 years out of 10. 12/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Union City compares
About 353 days separate Union City's last and first frost, putting it 2,216 of 40,283 ZIP codes nationally. Within CA, it ranks 996 of 2,555.
Learn more
zone vs. frost date covers why Zone 9b and Union City's frost date answer different questions. the frost range covers how to read the range around Union City's dates instead of trusting one.