Rancho Fontana Weather Forecast

    • 56
    • 78

    Becoming Sunny

    • 57
    • 81

    Mostly Sunny

    • 57
    • 83

    Mostly Sunny

    • 56
    • 81

    Mostly Sunny

    • 57
    • 81

    Mostly Sunny

    • 58
    • 85

    Mostly Sunny

Today 13 May San Bernardino and Riverside County Valleys-The Inland Empire

Partly cloudy with patchy fog in the morning. Becoming sunny. Highs 76 to 82. Areas of Winds southwest to 10 Mph becoming west with Gusts to 25 Mph in the afternoon.

Tonight 13 May San Bernardino and Riverside County Valleys-The Inland Empire

Mostly clear in the evening. Becoming partly cloudy. Lows 49 to 52 in wind Sheltered Areas to 50 to 56 in warmer Locations. Areas of Winds west 10 to 15 Mph with Gusts to 25 Mph in the evening becoming light.

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Rancho Fontana Temperature Statistics

May Temperature

Ontario International Airport (7.5 miles)

  • Lowest 6 May, 2026

    49.6 °F

  • Average May

    67.3 °F

  • Highest 10 May, 2026

    88 °F

Climate (2021–Present)

Ontario International Airport (7.5 miles)

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  • Average Low 2021–2026

    55.8 °F

  • Average 2021–2026

    67 °F

  • Average High 2021–2026

    79.4 °F
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