Steffan Reservoir Weather Forecast

    • 63
    • 83

    Chance Thunderstorms

    • 66
    • 86

    Slight Chance Thunderstorms

    • 61
    • 86

    Rain Showers Likely

    • 58
    • 77

    Chance Thunderstorms

    • 56
    • 75

    Slight Chance Thunderstorms

    • 54
    • 75

    Partly Sunny

Today 14 Sep Knox

Partly sunny with a slight chance of Showers in the Morning, then mostly cloudy with a chance of Showers and Thunderstorms in the afternoon. Highs in the lower 80s. South Winds 15 to 20 Mph with Gusts up to 30 Mph. Chance of rain 50 percent.

Tonight 14 Sep Knox

Mostly cloudy with a chance of Showers and Thunderstorms in the Evening, then partly cloudy with a slight chance of Showers after midnight. Lows in the lower 60s. South Winds 10 to 15 Mph with Gusts up to 25 Mph. Chance of rain 50 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Steffan Reservoir Temperature Statistics

September Temperature

Yankton, Chan Gurney Municipal Airport (11.2 miles)

  • Lowest 7 September, 2025

    41 °F

  • Average September

    63.5 °F

  • Highest 11 September, 2025

    84 °F

Climate (2020–Present)

Yankton, Chan Gurney Municipal Airport (11.2 miles)

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  • Average Low 2020–2025

    39 °F

  • Average 2020–2025

    50 °F

  • Average High 2020–2025

    61.2 °F
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