Fullerton Weather Forecast

    • 47
    • 63

    Rain Showers Likely

    • 44
    • 60

    Mostly Sunny

    • 45
    • 64

    Mostly Sunny

    • 46
    • 67

    Mostly Sunny

    • 49
    • 69

    Partly Sunny

    • 50
    • 68

    Chance Rain Showers

Today 26 Dec Orange County Inland

Showers and a slight chance of Thunderstorms. Locally heavy rainfall possible. Highs around 64 towards the coast to 60 to 63 farther inland. Areas of Winds south 10 to 15 Mph. Gusts to 30 Mph. Becoming 25 Mph this afternoon.

Tonight 26 Dec Orange County Inland

Mostly cloudy with a chance of Showers and a slight chance of Thunderstorms in the Evening, then partly cloudy overnight. Colder. Lows 44 to 49. Light Winds. Chance of measurable precipitation 50 percent.

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Fullerton Temperature Statistics

December Temperature

Fullerton, Fullerton Municipal Airport (3.1 miles)

  • Lowest 5 December, 2025

    45 °F

  • Average December

    60.5 °F

  • Highest 10 December, 2025

    84.9 °F

Climate (2020–Present)

Fullerton, Fullerton Municipal Airport (3.1 miles)

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  • Average Low 2020–2025

    56.8 °F

  • Average 2020–2025

    66.1 °F

  • Average High 2020–2025

    76.4 °F
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