Union City Weather Forecast

    • 64
    • 85

    Increasing Clouds

    • 64
    • 77

    Chance Rain Showers

    • 62
    • 76

    Chance Rain Showers

    • 61
    • 77

    Partly Sunny

    • 64
    • 81

    Mostly Sunny

    • 64
    • 84

    Slight Chance Rain Showers

Today 17 Sep San Francisco Bay Shoreline

Sunny. Highs in the 80s. Northwest Winds up to 5 Mph increasing to 10 to 20 Mph in the afternoon.

Tonight 17 Sep San Francisco Bay Shoreline

Partly cloudy in the evening then becoming mostly cloudy. Lows in the lower 60s. West Winds 10 to 20 Mph becoming southwest 5 to 10 Mph after midnight.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Union City Temperature Statistics

September Temperature

Hayward, Hayward Air Terminal (6.2 miles)

  • Lowest 1 September, 2025

    60.1 °F

  • Average September

    66.3 °F

  • Highest 1 September, 2025

    82.9 °F

Climate (2020–Present)

Hayward, Hayward Air Terminal (6.2 miles)

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  • Average Low 2020–2025

    52 °F

  • Average 2020–2025

    59.3 °F

  • Average High 2020–2025

    69 °F
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