The Arboretum Weather Forecast

    • 77
    • 99

    Hot

    • 76
    • 102

    Hot

    • 73
    • 99

    Hot

    • 65
    • 93

    Mostly Sunny

    • 62
    • 90

    Mostly Sunny

    • 63
    • 89

    Mostly Sunny

    • 62
    • 89

    Mostly Sunny

Today 8 Sep Los Angeles County San Gabriel Valley

Mostly cloudy in the morning then partly cloudy. A 20 percent chance of Showers and Thunderstorms. Highs 92 to 102.

Tonight 8 Sep Los Angeles County San Gabriel Valley

Partly cloudy in the evening then mostly clear. Lows in the mid 70s to around 80.

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The Arboretum Temperature Statistics

September Temperature

El Monte (4.3 miles)

  • Lowest 2 September, 2026

    64.4 °F

  • Average September

    78.2 °F

  • Highest 5 September, 2026

    91.4 °F

Climate (2021–2026)

El Monte (4.3 miles)

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  • Average Low 2021–2026

    59.9 °F

  • Average 2021–2026

    70.7 °F

  • Average High 2021–2026

    77.3 °F
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