Plum Island Weather Forecast

    • 59
    • 80

    Mostly Sunny

    • 64
    • 82

    Partly Sunny

    • 55
    • 81

    Mostly Sunny

    • 52
    • 72

    Mostly Sunny

    • 49
    • 69

    Mostly Sunny

    • 49
    • 71

    Partly Sunny

Today 21 Aug La Salle

Partly cloudy in the Morning, then becoming mostly sunny. Patchy fog through mid morning. Highs in the upper 70s. Northeast Winds 5 to 10 Mph.

Tonight 21 Aug La Salle

Mostly clear. Lows around 60. Northeast Winds around 5 Mph in the Evening, becoming light and variable.

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Plum Island Temperature Statistics

August Temperature

Illinois Valley Regional Airport (8.1 miles)

  • Lowest 3 August, 2025

    53.6 °F

  • Average August

    74.8 °F

  • Highest 16 August, 2025

    91.4 °F

Climate (2020–Present)

Illinois Valley Regional Airport (8.1 miles)

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  • Average Low 2020–2025

    43.2 °F

  • Average 2020–2025

    52.6 °F

  • Average High 2020–2025

    62.1 °F
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