Fontana Weather Forecast

    • 54
    • 80

    Mostly Sunny

    • 55
    • 77

    Mostly Sunny

    • 57
    • 83

    Mostly Sunny

    • 55
    • 80

    Mostly Sunny

    • 55
    • 78

    Partly Sunny

    • 54
    • 77

    Partly Sunny

    • 53
    • 78

    Partly Sunny

Today 16 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 78 to 82. Areas of Winds east to 10 Mph becoming west 10 Mph this afternoon.

Tonight 16 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy. Lows 46 to 50 in wind Sheltered Areas to 51 to 58 in warmer Locations. Light Winds.

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Fontana Temperature Statistics

December Temperature

Ontario International Airport (8.1 miles)

  • Lowest 2 December, 2025

    46 °F

  • Average December

    61.3 °F

  • Highest 10 December, 2025

    84.9 °F

Climate (2020–Present)

Ontario International Airport (8.1 miles)

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  • Average Low 2020–2025

    55.5 °F

  • Average 2020–2025

    66.6 °F

  • Average High 2020–2025

    78.9 °F
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