Mount Vernon Weather Forecast

    • 59
    • 87

    Sunny

    • 63
    • 87

    Sunny

    • 69
    • 92

    Chance Rain Showers

    • 66
    • 87

    Chance Rain Showers

    • 67
    • 90

    Slight Chance Rain Showers

    • 68
    • 92

    Mostly Sunny

Today 3 Sep San Bernardino and Riverside County Valleys-The Inland Empire

Sunny. Highs 83 to 88. Areas of Winds south to 10 Mph becoming southwest with Gusts to 25 Mph this afternoon.

Tonight 3 Sep San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Patchy fog overnight. Lows 52 to 59. Areas of Winds southwest 10 to 15 Mph with Gusts to 25 Mph in the evening becoming light.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Mount Vernon Temperature Statistics

September Temperature

San Bernardino Intl. Airport (4.3 miles)

  • Lowest 1 September, 2026

    62.6 °F

  • Average September

    73.3 °F

  • Highest 1 September, 2026

    91.4 °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

    80.4 °F
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