Union City, CA Weather & Growing Conditions
Today
84°F
Sunny
Sunny. High near 84, with temperatures falling to around 80 in the afternoon. West northwest wind 2 to 12 mph, with gusts as high as 18 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 84°F | Sunny | 2 to 12 mph WNW | 0% |
| Tonight | 59°F | Mostly Clear | 2 to 10 mph NNW | 0% |
| Wednesday | 82°F | Sunny | 2 to 12 mph NW | 0% |
| Wednesday Night | 60°F | Mostly Clear | 2 to 12 mph W | 0% |
| Thursday | 80°F | Sunny | 2 to 12 mph W | 0% |
| Thursday Night | 61°F | Mostly Clear | 2 to 12 mph WNW | 0% |
| Friday | 84°F | Mostly Sunny | 2 to 12 mph WNW | 0% |
| Friday Night | 62°F | Mostly Clear | 2 to 12 mph W | 0% |
| Saturday | 83°F | Sunny | 2 to 12 mph W | 0% |
| Saturday Night | 63°F | Mostly Clear | 3 to 12 mph W | 0% |
| Sunday | 79°F | Sunny | 3 to 12 mph W | 0% |
| Sunday Night | 60°F | Partly Cloudy | 6 to 12 mph WSW | 0% |
| Monday | 76°F | Mostly Sunny | 6 to 13 mph W | 0% |
| Monday Night | 59°F | Partly Cloudy | 5 to 13 mph W | 0% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Union City, CA
Last spring frost
Jan 7
First fall frost
Dec 22
Growing season
353 days
Hardiness zone
10a
Explore more for Union City, CA: full frost dates · planting calendar · California frost dates
Climate data from the nearest NOAA station, Fremont, Ca (4.6 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.