Union City, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union City, a city in Alameda County, California.
Today
87°F
Sunny
Sunny. High near 87, with temperatures falling to around 84 in the afternoon. West wind 1 to 10 mph.
7-day forecast for Union City
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 87°F | Sunny | 1 to 10 mph W | 0% |
| Tonight | 59°F | Mostly Clear | 1 to 9 mph NW | 0% |
| Wednesday | 86°F | Sunny | 1 to 10 mph WNW | 0% |
| Wednesday Night | 60°F | Mostly Clear | 1 to 10 mph W | 0% |
| Thursday | 84°F | Mostly Sunny | 1 to 10 mph W | 0% |
| Thursday Night | 60°F | Mostly Clear | 2 to 10 mph W | 0% |
| Friday | 87°F | Mostly Sunny | 2 to 9 mph W | 0% |
| Friday Night | 62°F | Mostly Clear | 2 to 9 mph W | 0% |
| Saturday | 86°F | Sunny | 2 to 10 mph W | 0% |
| Saturday Night | 63°F | Mostly Clear | 3 to 10 mph W | 0% |
| Sunday | 81°F | Sunny | 3 to 10 mph WSW | 0% |
| Sunday Night | 60°F | Partly Cloudy | 6 to 10 mph WSW | 0% |
| Monday | 77°F | Mostly Sunny | 6 to 12 mph WSW | 0% |
| Monday Night | 58°F | Partly Cloudy | 5 to 12 mph WSW | 0% |
Forecast source: National Weather Service (api.weather.gov) for Union City (37.603, -122.019). Updated through the day.
Growing snapshot for Union City
Last spring frost
Jan 2
First fall frost
Dec 25
Growing season
365 days
Hardiness zone
9b
More local growing data for Union City: nearby ZIP 94544 weather · frost dates · planting calendar · California frost dates
Nearby towns & communities
Alameda
Albany
Ashland
Berkeley
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Cherryland
Dublin
Emeryville
Fairview
Fremont
Hayward
Kensington
Livermore
Mountain House
Newark
Oakland
Piedmont
Pleasanton
San Leandro
San Lorenzo
Sunol
Climate data from the nearest NOAA station, Hayward Air Terminal, Ca (3.5 mi from Union City). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.