Cucamonga-Guasti Regional Park Weather Forecast

    • 55
    • 79

    Increasing Clouds

    • 53
    • 79

    Mostly Sunny

    • 54
    • 82

    Mostly Sunny

    • 54
    • 83

    Mostly Sunny

    • 53
    • 77

    Partly Sunny

    • 54
    • 77

    Partly Sunny

Today 13 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 78 to 82. Light Winds.

Tonight 13 Dec San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy. Lows 49 to 52 in wind Sheltered Areas to 53 to 59 in warmer Locations. Light Winds.

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Cucamonga-Guasti Regional Park Temperature Statistics

December Temperature

Ontario International Airport (1.2 miles)

  • Lowest 2 December, 2025

    46 °F

  • Average December

    61.1 °F

  • Highest 10 December, 2025

    84.9 °F

Climate (2020–Present)

Ontario International Airport (1.2 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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