Union City Weather Forecast

    • 53
    • 74

    Increasing Clouds

    • 50
    • 70

    Becoming Sunny

    • 52
    • 77

    Mostly Sunny

    • 51
    • 77

    Mostly Sunny

    • 51
    • 72

    Mostly Sunny

    • 53
    • 76

    Mostly Sunny

    • 56
    • 84

    Mostly Sunny

Today 12 May San Francisco Bay Shoreline

Partly cloudy. Highs in the upper 60s to mid 70s. West Winds 10 to 20 Mph.

Tonight 12 May San Francisco Bay Shoreline

Partly cloudy in the evening then becoming mostly cloudy. Lows in the mid 50s. West Winds 10 to 20 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Union City Temperature Statistics

May Temperature

Hayward, Hayward Air Terminal (6.2 miles)

  • Lowest 4 May, 2026

    53.7 °F

  • Average May

    59.9 °F

  • Highest 6 May, 2026

    70.6 °F

Climate (2021–Present)

Hayward, Hayward Air Terminal (6.2 miles)

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  • Average Low 2021–2026

    52.3 °F

  • Average 2021–2026

    59.6 °F

  • Average High 2021–2026

    69.1 °F
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