Fullerton Weather Forecast

    • 48
    • 68

    Sunny

    • 49
    • 73

    Sunny

    • 55
    • 77

    Sunny

    • 55
    • 81

    Mostly Sunny

    • 53
    • 80

    Mostly Sunny

    • 53
    • 79

    Sunny

Today 6 Dec Los Angeles County San Gabriel Valley

Sunny. Highs in the upper 60s to mid 70s.

Tonight 6 Dec Los Angeles County San Gabriel Valley

Clear. Lows in the mid 40s to around 50.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Fullerton Temperature Statistics

December Temperature

Fullerton, Fullerton Municipal Airport (6.2 miles)

  • Lowest 2 December, 2025

    48 °F

  • Average December

    58.5 °F

  • Highest 1 December, 2025

    72 °F

Climate (2020–Present)

Fullerton, Fullerton Municipal Airport (6.2 miles)

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2020–2025

    56.8 °F

  • Average 2020–2025

    66 °F

  • Average High 2020–2025

    76.4 °F
Get WillyWeather+ to remove ads