Union City Weather Forecast

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    Rain

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    Rain

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    Rain

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    Rain

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    Rain

Today 19 Dec San Francisco Bay Shoreline

Rain. Highs in the lower to mid 60s. South Winds 10 to 20 Mph.

Tonight 19 Dec San Francisco Bay Shoreline

Rain. Lows in the mid 50s. South Winds 10 to 20 Mph. Becoming 5 to 10 Mph after midnight.

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Union City Temperature Statistics

December Temperature

Hayward, Hayward Air Terminal (6.2 miles)

  • Lowest 3 December, 2025

    41 °F

  • Average December

    48.6 °F

  • Highest 3 December, 2025

    64.9 °F

Climate (2020–Present)

Hayward, Hayward Air Terminal (6.2 miles)

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  • Average Low 2020–2025

    52 °F

  • Average 2020–2025

    59.2 °F

  • Average High 2020–2025

    68.8 °F
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