Rancho Fontana Weather Forecast

    • 56
    • 84

    Sunny

    • 55
    • 82

    Mostly Sunny

    • 54
    • 78

    Partly Sunny

    • 53
    • 78

    Mostly Sunny

    • 54
    • 79

    Mostly Sunny

    • 55
    • 78

    Mostly Sunny

Today 11 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Sunny. Highs 82 to 87. Areas of Winds north to 10 Mph becoming west 10 Mph this afternoon.

Tonight 11 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Clear. Lows 48 to 52 in wind Sheltered Areas to 52 to 59 in warmer Locations. Light Winds.

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Rancho Fontana Temperature Statistics

December Temperature

Ontario International Airport (7.5 miles)

  • Lowest 2 December, 2025

    46 °F

  • Average December

    59.1 °F

  • Highest 8 December, 2025

    81 °F

Climate (2020–Present)

Ontario International Airport (7.5 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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