Rancho Cucamonga Weather Forecast

    • 51
    • 77

    Mostly Sunny

    • 51
    • 73

    Mostly Cloudy

    • 50
    • 67

    Mostly Cloudy

    • 49
    • 67

    Partly Sunny

    • 47
    • 69

    Mostly Sunny

    • 48
    • 72

    Partly Sunny

Today 20 Jan San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 74 to 79. Areas of Winds east to 10 Mph becoming north 10 Mph in the afternoon.

Tonight 20 Jan San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 44 to 47 in wind Sheltered Areas to 48 to 54 in warmer Locations. Light Winds.

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Rancho Cucamonga Temperature Statistics

January Temperature

Ontario International Airport (3.7 miles)

  • Lowest 11 January, 2026

    43 °F

  • Average January

    59.4 °F

  • Highest 14 January, 2026

    84 °F

Climate (2021–Present)

Ontario International Airport (3.7 miles)

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  • Average Low 2021–2026

    55.6 °F

  • Average 2021–2026

    66.6 °F

  • Average High 2021–2026

    78.9 °F
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