Ontario Weather Forecast

    • 59
    • 86

    Mostly Sunny

    • 61
    • 89

    Becoming Sunny

    • 62
    • 94

    Mostly Sunny

    • 58
    • 84

    Partly Sunny

    • 57
    • 80

    Mostly Sunny

    • 57
    • 80

    Mostly Sunny

    • 57
    • 81

    Mostly Sunny

Today 9 May San Bernardino and Riverside County Valleys-The Inland Empire

Mostly sunny. Highs 85 to 91. Areas of Winds west to 10 Mph. Becoming 10 to 15 Mph with Gusts to 25 Mph this afternoon.

Tonight 9 May San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear. Lows 52 to 55 in wind Sheltered Areas to 54 to 62 in warmer Locations. Areas of Winds west to 10 Mph with Gusts to 25 Mph this evening becoming light.

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Ontario Temperature Statistics

May Temperature

Ontario International Airport (3.7 miles)

  • Lowest 6 May, 2026

    49.6 °F

  • Average May

    65.4 °F

  • Highest 7 May, 2026

    82.9 °F

Climate (2021–Present)

Ontario International Airport (3.7 miles)

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  • Average Low 2021–2026

    55.8 °F

  • Average 2021–2026

    67 °F

  • Average High 2021–2026

    79.3 °F
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