Fontana Weather Forecast

    • 49
    • 72

    Mostly Sunny

    • 51
    • 76

    Mostly Sunny

    • 53
    • 78

    Mostly Sunny

    • 54
    • 82

    Mostly Sunny

    • 54
    • 81

    Sunny

    • 54
    • 80

    Sunny

    • 54
    • 82

    Mostly Sunny

Today 6 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Sunny. Highs 69 to 73. Light Winds becoming west to 10 Mph this afternoon.

Tonight 6 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 43 to 47 in wind Sheltered Areas to 46 to 52 in warmer Locations. Areas of Winds east to 10 Mph becoming north overnight.

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Fontana Temperature Statistics

December Temperature

Ontario International Airport (8.1 miles)

  • Lowest 2 December, 2025

    46 °F

  • Average December

    58.4 °F

  • Highest 1 December, 2025

    73 °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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