Fontana Weather Forecast

    • 63
    • 85

    Mostly Cloudy

    • 63
    • 87

    Partly Sunny

    • 65
    • 90

    Mostly Sunny

    • 66
    • 92

    Mostly Sunny

    • 67
    • 94

    Partly Sunny

    • 68
    • 95

    Mostly Sunny

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

Mostly cloudy. Highs 82 to 88. Areas of Winds south to 10 Mph becoming southwest with Gusts to 25 Mph this afternoon.

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

Mostly cloudy in the evening. Becoming partly cloudy. Lows 57 to 63. Areas of Winds west 10 to 15 Mph with Gusts to 25 Mph in the evening becoming light.

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Fontana Temperature Statistics

August Temperature

Ontario International Airport (8.1 miles)

  • Lowest 5 August, 2026

    66.7 °F

  • Average August

    84.1 °F

  • Highest 1 August, 2026

    102.7 °F

Climate (2021–2026)

Ontario International Airport (8.1 miles)

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  • Average Low 2021–2026

    55.8 °F

  • Average 2021–2026

    67.1 °F

  • Average High 2021–2026

    79.3 °F
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