Mount Vernon Weather Forecast

    • 62
    • 84

    Mostly Sunny

    • 65
    • 89

    Mostly Sunny

    • 64
    • 86

    Partly Sunny

    • 62
    • 82

    Mostly Sunny

    • 66
    • 87

    Sunny

    • 69
    • 95

    Mostly Sunny

    • 70
    • 96

    Mostly Sunny

Today 18 Sep San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 90 to 96.

Tonight 18 Sep San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 53 to 61. Areas of Winds west to 10 Mph this evening becoming light.

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Mount Vernon Temperature Statistics

September Temperature

San Bernardino Intl. Airport (4.3 miles)

  • Lowest 2 September, 2026

    59 °F

  • Average September

    75.8 °F

  • Highest 9 September, 2026

    105.8 °F

Climate (2021–2026)

San Bernardino Intl. Airport (4.3 miles)

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  • Average Low 2021–2026

    54.2 °F

  • Average 2021–2026

    63.2 °F

  • Average High 2021–2026

    80.3 °F
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