Waterloo Weather Forecast

    • 58
    • 68

    Mostly Cloudy

    • 57
    • 69

    Mostly Cloudy

    • 57
    • 68

    Mostly Cloudy

    • 53
    • 72

    Mostly Cloudy

    • 48
    • 70

    Partly Sunny

    • 51
    • 71

    Mostly Cloudy

    • 54
    • 74

    Partly Sunny

Today 21 Sep Johnson

Partly cloudy through early Afternoon, then clearing. Highs in the upper 70s.

Tonight 21 Sep Johnson

Mostly cloudy. A slight chance of Showers late this afternoon. Lows in the upper 50s. Northeast Winds 10 to 15 Mph. Chance of rain 20 percent.

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Waterloo Temperature Statistics

September Temperature

Indianapolis International Airport (11.8 miles)

  • Lowest 14 September, 2026

    58.6 °F

  • Average September

    79.4 °F

  • Highest 4 September, 2026

    97.6 °F

Climate (2021–2026)

Indianapolis International Airport (11.8 miles)

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  • Average Low 2021–2026

    46.8 °F

  • Average 2021–2026

    55.8 °F

  • Average High 2021–2026

    65.3 °F
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