Diamond Bar Weather Forecast

    • 48
    • 74

    Sunny

    • 54
    • 79

    Sunny

    • 55
    • 82

    Sunny

    • 54
    • 80

    Sunny

    • 54
    • 80

    Sunny

    • 53
    • 81

    Sunny

Today 7 Dec Los Angeles County San Gabriel Valley

Sunny. Highs in the lower to mid 70s.

Tonight 7 Dec Los Angeles County San Gabriel Valley

Mostly clear. Lows in the mid 40s to lower 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

    59.2 °F

  • Highest 1 December, 2025

    69.8 °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

    75.5 °F
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