Diamond Bar Weather Forecast

    • 46
    • 74

    Increasing Clouds

    • 47
    • 72

    Partly Sunny

    • 50
    • 81

    Mostly Sunny

    • 53
    • 83

    Mostly Sunny

    • 53
    • 84

    Partly Sunny

    • 51
    • 76

    Partly Sunny

    • 48
    • 71

    Partly Sunny

Today 27 Jan Los Angeles County San Gabriel Valley

Sunny. Highs in the lower to mid 70s.

Tonight 27 Jan Los Angeles County San Gabriel Valley

Partly cloudy in the evening then mostly cloudy. Lows in the 40s except the lower to mid 50s in the Hills.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Diamond Bar Temperature Statistics

January Temperature

Brackett Field Airport (4.3 miles)

  • Lowest 10 January, 2026

    35.6 °F

  • Average January

    60.7 °F

  • Highest 14 January, 2026

    82.4 °F

Climate (2021–Present)

Brackett Field Airport (4.3 miles)

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  • Average Low 2021–2026

    55.6 °F

  • Average 2021–2026

    67.7 °F

  • Average High 2021–2026

    75.6 °F
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