Fontana Weather Forecast

    • 68
    • 96

    Mostly Sunny

    • 69
    • 96

    Mostly Sunny

    • 70
    • 98

    Hot

    • 70
    • 98

    Hot

    • 71
    • 100

    Hot

    • 69
    • 99

    Hot

Today 4 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 93 to 102. Light Winds becoming west 10 to 15 Mph with Gusts to 25 Mph this afternoon.

Tonight 4 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 62 to 68. 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 2 August, 2026

    70 °F

  • Average August

    84.6 °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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