Downtown Fullerton Weather Forecast

    • 67
    • 86

    Increasing Clouds

    • 66
    • 82

    Mostly Cloudy

    • 65
    • 82

    Mostly Sunny

    • 66
    • 84

    Mostly Sunny

    • 66
    • 86

    Mostly Sunny

    • 67
    • 87

    Partly Sunny

Today 12 Aug Orange County Inland

Patchy fog this morning. Partly cloudy. Highs 81 to 85. Areas of Winds southwest to 10 Mph.

Tonight 12 Aug Orange County Inland

Mostly cloudy. Patchy fog overnight. Lows 59 to 67. Areas of Winds southwest 10 Mph this evening becoming light.

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Downtown Fullerton Temperature Statistics

August Temperature

Fullerton, Fullerton Municipal Airport (3.1 miles)

  • Lowest 5 August, 2026

    67.6 °F

  • Average August

    80.1 °F

  • Highest 8 August, 2026

    97.6 °F

Climate (2021–2026)

Fullerton, Fullerton Municipal Airport (3.1 miles)

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  • Average Low 2021–2026

    57 °F

  • Average 2021–2026

    66.5 °F

  • Average High 2021–2026

    76.8 °F
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