Fontana Weather Forecast

    • 76
    • 104

    Hot

    • 76
    • 106

    Hot

    • 77
    • 106

    Hot

    • 75
    • 105

    Hot

    • 72
    • 101

    Hot

    • 68
    • 96

    Mostly Sunny

Today 25 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 102 to 108. Areas of Winds west to 10 Mph. Becoming 10 to 15 Mph with Gusts to 25 Mph this afternoon.

Tonight 25 Aug San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 71 to 76. 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 °F

  • Highest 23 August, 2026

    105.1 °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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