Union City, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union City, a city in Alameda County, California.
This Afternoon
66°F
Sunny
Sunny. High near 66, with temperatures falling to around 63 in the afternoon. West northwest wind 6 to 9 mph.
7-day forecast for Union City
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 66°F | Sunny | 6 to 9 mph WNW | 1% |
| Tonight | 50°F | Mostly Cloudy | 1 to 5 mph NE | 1% |
| Thursday | 70°F | Sunny | 1 to 6 mph NW | 0% |
| Thursday Night | 50°F | Mostly Clear | 5 mph ENE | 0% |
| Friday | 71°F | Mostly Sunny | 2 to 6 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 W | 0% |
| Sunday | 72°F | Mostly Sunny | 1 to 6 mph N | 0% |
| Sunday Night | 53°F | Partly Cloudy | 0 to 6 mph SW | 0% |
| Monday | 70°F | Partly Sunny | 1 to 6 mph SW | 0% |
| Monday Night | 52°F | Partly Cloudy | 1 to 6 mph SW | 1% |
| Tuesday | 71°F | Mostly Sunny | 1 to 6 mph NNE | 1% |
| Tuesday Night | 54°F | Partly Cloudy | 2 to 6 mph WSW | 8% |
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
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Berkeley
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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.