Rancho Fontana Weather Forecast

    • 67
    • 93

    Increasing Clouds

    • 67
    • 88

    Partly Sunny

    • 69
    • 92

    Mostly Sunny

    • 69
    • 94

    Sunny

    • 68
    • 96

    Sunny

    • 68
    • 95

    Mostly Sunny

Today 27 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 89 to 96. Light Winds becoming west 10 to 15 Mph with Gusts to 25 Mph in the afternoon.

Tonight 27 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy in the evening. Becoming mostly cloudy overnight with patchy fog. Lows 62 to 67. Areas of Winds southwest 10 Mph in the evening becoming light.

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Rancho Fontana Temperature Statistics

August Temperature

Ontario International Airport (7.5 miles)

  • Lowest 1 August, 2025

    61.6 °F

  • Average August

    81 °F

  • Highest 7 August, 2025

    103.6 °F

Climate (2020–Present)

Ontario International Airport (7.5 miles)

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  • Average Low 2020–2025

    55.5 °F

  • Average 2020–2025

    66.7 °F

  • Average High 2020–2025

    79.1 °F
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