Fontana Weather Forecast

    • 73
    • 103

    Hot

    • 70
    • 99

    Hot

    • 66
    • 95

    Sunny

    • 65
    • 91

    Mostly Sunny

    • 67
    • 89

    Slight Chance Rain Showers

    • 67
    • 90

    Partly Sunny

    • 66
    • 91

    Partly Sunny

Today 28 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy. Highs 101 to 107. Areas of Winds west to 10 Mph. Becoming 10 to 15 Mph with Gusts to 30 Mph this afternoon.

Tonight 28 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 68 to 73. Areas of Winds west 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

    84.6 °F

  • Highest 23 August, 2026

    105.7 °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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