Three Mile Island Weather Forecast

    • 32
    • 41

    Increasing Clouds

    • 22
    • 42

    Partly Sunny

    • 28
    • 38

    Mostly Cloudy

    • 33
    • 45

    Mostly Cloudy

    • 31
    • 46

    Mostly Cloudy

    • 43
    • 51

    Slight Chance Rain Showers

Today 20 Dec Dauphin

Mostly sunny. Much cooler with Highs in the upper 30s. West Winds 5 to 10 Mph, becoming south in the afternoon. Gusts up to 25 Mph.

Tonight 20 Dec Dauphin

Mostly clear and much cooler. Near steady temperature in the mid 20s. Northwest Winds 10 to 15 Mph with Gusts up to 30 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Three Mile Island Temperature Statistics

December Temperature

Harrisburg, Harrisburg International Airport (3.7 miles)

  • Lowest 16 December, 2025

    9 °F

  • Average December

    28.7 °F

  • Highest 1 December, 2025

    42.1 °F

Climate (2020–Present)

Harrisburg, Harrisburg International Airport (3.7 miles)

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  • Average Low 2020–2025

    47.5 °F

  • Average 2020–2025

    56 °F

  • Average High 2020–2025

    65.1 °F
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