Ontario Weather Forecast

    • 55
    • 77

    Decreasing Clouds

    • 54
    • 77

    Partly Sunny

    • 51
    • 73

    Partly Sunny

    • 51
    • 71

    Partly Sunny

    • 53
    • 72

    Mostly Sunny

    • 56
    • 78

    Mostly Sunny

Today 18 May San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy in the morning. Becoming mostly sunny. Warmer. Highs 77 to 82. Light Winds becoming west 15 Mph in the afternoon.

Tonight 18 May San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear in the evening. Becoming partly cloudy. Lows 50 to 55. Light Winds.

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Ontario Temperature Statistics

May Temperature

Ontario International Airport (3.7 miles)

  • Lowest 3 May, 2021

    55 °F
  • Average May

    65.7 °F
  • Highest 4 May, 2021

    90 °F

Climate (2010–Present)

Ontario International Airport (3.7 miles)

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  • Average Low 2010–Present

    55.9 °F
  • Average 2010–Present

    66.1 °F
  • Average High 2010–Present

    79 °F
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