Rialto Weather Forecast

    • 62
    • 86

    Becoming Sunny

    • 64
    • 90

    Mostly Sunny

    • 65
    • 93

    Sunny

    • 67
    • 95

    Mostly Sunny

    • 69
    • 96

    Partly Sunny

    • 68
    • 93

    Slight Chance Thunderstorms

Today 13 Sep San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy with patchy fog in the morning. Becoming mostly sunny. Highs 82 to 88. Light Winds becoming west 10 Mph in the afternoon.

Tonight 13 Sep San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 56 to 61. Areas of Winds west to 10 Mph in the evening becoming light.

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Rialto Temperature Statistics

September Temperature

San Bernardino Intl. Airport (6.8 miles)

  • Lowest 9 September, 2025

    60.8 °F

  • Average September

    78 °F

  • Highest 1 September, 2025

    100.4 °F

Climate (2020–Present)

San Bernardino Intl. Airport (6.8 miles)

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  • Average Low 2020–2025

    54.1 °F

  • Average 2020–2025

    63.2 °F

  • Average High 2020–2025

    80.5 °F
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