Alta Loma Weather Forecast

    • 51
    • 67

    Mostly Cloudy

    • 53
    • 71

    Partly Sunny

    • 58
    • 80

    Mostly Sunny

    • 61
    • 86

    Sunny

    • 60
    • 86

    Mostly Sunny

    • 60
    • 85

    Mostly Sunny

Today 28 May San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy. Highs 65 to 70. Areas of Winds south to 10 Mph becoming southwest with Gusts to 25 Mph this afternoon.

Tonight 28 May San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy in the Evening, then cloudy with a slight chance of light Showers overnight. Lows 46 to 54. Areas of Winds southwest 10 to 15 Mph. Gusts to 30 Mph in the evening. Chance of measurable precipitation 20 percent.

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Alta Loma Temperature Statistics

May Temperature

Ontario International Airport (4.3 miles)

  • Lowest 6 May, 2026

    49.6 °F

  • Average May

    68.7 °F

  • Highest 11 May, 2026

    96.7 °F

Climate (2021–Present)

Ontario International Airport (4.3 miles)

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  • Average Low 2021–2026

    55.8 °F

  • Average 2021–2026

    67.1 °F

  • Average High 2021–2026

    79.4 °F
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