Fontana Weather Forecast

    • 62
    • 91

    Mostly Sunny

    • 60
    • 89

    Mostly Sunny

    • 59
    • 88

    Mostly Sunny

    • 60
    • 88

    Mostly Sunny

    • 64
    • 88

    Mostly Sunny

    • 67
    • 88

    Partly Sunny

    • 69
    • 89

    Partly Sunny

Today 31 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 89 to 94. Areas of Winds south to 10 Mph becoming southwest with Gusts to 25 Mph this afternoon.

Tonight 31 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 57 to 62. Areas of Winds southwest 10 to 15 Mph with Gusts to 25 Mph this evening becoming light.

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Fontana Temperature Statistics

August Temperature

Ontario International Airport (8.1 miles)

  • Lowest 15 August, 2026

    65.6 °F

  • Average August

    85.2 °F

  • Highest 26 August, 2026

    106.6 °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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