Union City, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union City, a city in Alameda County, California.
Overnight
50°F
Partly Cloudy
Partly cloudy. Low around 50, with temperatures rising to around 52 overnight. Northeast wind 5 to 8 mph.
7-day forecast for Union City
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 50°F | Partly Cloudy | 5 to 8 mph NE | 0% |
| Wednesday | 66°F | Sunny | 2 to 9 mph NNW | 2% |
| Wednesday Night | 51°F | Mostly Cloudy | 1 to 6 mph ENE | 2% |
| Thursday | 70°F | Mostly Sunny | 1 to 6 mph N | 0% |
| Thursday Night | 49°F | Mostly Clear | 1 to 5 mph NNW | 0% |
| Friday | 72°F | Sunny | 5 mph NNE | 0% |
| Friday Night | 50°F | Mostly Clear | 0 to 5 mph NE | 0% |
| Saturday | 75°F | Sunny | 1 to 5 mph N | 0% |
| Saturday Night | 52°F | Mostly Clear | 1 to 5 mph WNW | 0% |
| Sunday | 72°F | Mostly Sunny | 1 to 5 mph N | 0% |
| Sunday Night | 53°F | Partly Cloudy | 1 to 5 mph SSW | 0% |
| Monday | 70°F | Mostly Sunny | 1 to 6 mph SSW | 2% |
| Monday Night | 52°F | Partly Cloudy | 2 to 6 mph SSW | 2% |
| Tuesday | 70°F | Mostly Sunny | 0 to 5 mph N | 5% |
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 Nov 4, 2026.