Rancho Cucamonga Weather Forecast

    • 71
    • 97

    Hot

    • 74
    • 101

    Hot

    • 73
    • 100

    Hot

    • 73
    • 97

    Hot

    • 71
    • 97

    Hot

    • 68
    • 94

    Slight Chance Thunderstorms

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

Mostly sunny. Highs 95 to 102. Light Winds becoming west 10 to 15 Mph this afternoon.

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

Partly cloudy. Lows 66 to 71. Areas of Winds west to 10 Mph in the evening becoming light.

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Rancho Cucamonga Temperature Statistics

August Temperature

Ontario International Airport (3.7 miles)

  • Lowest 1 August, 2025

    61.6 °F

  • Average August

    79.2 °F

  • Highest 7 August, 2025

    103.6 °F

Climate (2020–Present)

Ontario International Airport (3.7 miles)

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  • Average Low 2020–2025

    55.5 °F

  • Average 2020–2025

    66.7 °F

  • Average High 2020–2025

    79.1 °F
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