Cook County Forest Preserve Weather Forecast

    • 64
    • 81

    Mostly Sunny

    • 65
    • 84

    Mostly Sunny

    • 65
    • 86

    Partly Sunny

    • 66
    • 86

    Partly Sunny

    • 64
    • 83

    Chance Thunderstorms

    • 59
    • 76

    Chance Thunderstorms

Today 14 Sep Northern Cook

Mostly sunny. Patchy fog through mid morning. Highs in the lower 80s Inland, but only in the mid 70s near the lake. East Winds 5 to 10 Mph.

Tonight 14 Sep Northern Cook

Clear. Lows in the lower 60s. East Winds 5 to 10 Mph.

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Cook County Forest Preserve Temperature Statistics

September Temperature

Chicago, Chicago-O'Hare International Airport (2.5 miles)

  • Lowest 7 September, 2025

    46.9 °F

  • Average September

    64 °F

  • Highest 10 September, 2025

    82 °F

Climate (2020–Present)

Chicago, Chicago-O'Hare International Airport (2.5 miles)

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  • Average Low 2020–2025

    45.3 °F

  • Average 2020–2025

    53.4 °F

  • Average High 2020–2025

    61.7 °F
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