Diamond Bar Weather Forecast

    • 49
    • 72

    Becoming Sunny

    • 51
    • 74

    Mostly Sunny

    • 50
    • 74

    Mostly Sunny

    • 49
    • 71

    Mostly Sunny

    • 50
    • 79

    Mostly Sunny

    • 52
    • 75

    Partly Sunny

Today 14 Dec Los Angeles County San Gabriel Valley

Low Clouds and fog in the morning then partly cloudy. Highs in the mid 60s to mid 70s.

Tonight 14 Dec Los Angeles County San Gabriel Valley

Clear. Lows in the mid 40s to mid 50s.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Diamond Bar Temperature Statistics

December Temperature

Brackett Field Airport (4.3 miles)

  • Lowest 5 December, 2025

    42.8 °F

  • Average December

    64.3 °F

  • Highest 10 December, 2025

    86 °F

Climate (2020–Present)

Brackett Field Airport (4.3 miles)

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  • Average Low 2020–2025

    55.5 °F

  • Average 2020–2025

    67.6 °F

  • Average High 2020–2025

    75.6 °F
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