Fullerton Weather Forecast

    • 52
    • 77

    Mostly Sunny

    • 55
    • 74

    Mostly Sunny

    • 56
    • 81

    Mostly Cloudy

    • 54
    • 77

    Patchy Fog

    • 54
    • 71

    Mostly Cloudy

    • 53
    • 71

    Mostly Cloudy

Today 16 Dec Los Angeles County San Gabriel Valley

Sunny except for patchy low Clouds and dense fog in the morning. Visibility one quarter mile or less. Highs around 80.

Tonight 16 Dec Los Angeles County San Gabriel Valley

Clear except for patchy low Clouds and fog after midnight. Fog locally dense with visibility one quarter mile or less. Lows in the upper 40s and 50s.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Fullerton Temperature Statistics

December Temperature

Fullerton, Fullerton Municipal Airport (6.2 miles)

  • Lowest 5 December, 2025

    45 °F

  • Average December

    61.8 °F

  • Highest 10 December, 2025

    84.9 °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

    66.1 °F

  • Average High 2020–2025

    76.5 °F
Get WillyWeather+ to remove ads