Steffan Reservoir Weather Forecast

    • 61
    • 70

    Chance Rain Showers

    • 60
    • 72

    Mostly Cloudy

    • 61
    • 72

    Mostly Cloudy

    • 58
    • 67

    Rain Showers Likely

    • 56
    • 67

    Chance Rain Showers

    • 53
    • 66

    Chance Rain Showers

Today 26 Sep Knox

Patchy fog early this morning. Mostly cloudy with a slight chance of Thunderstorms. Showers Likely, mainly early. Humid with Highs in the lower 70s. South Winds 10 to 15 Mph with Gusts up to 25 Mph. Chance of rain 70 percent.

Tonight 26 Sep Knox

Mostly cloudy. A slight chance of Showers in the evening. Areas of fog after midnight. Lows around 60. Southeast Winds 5 to 10 Mph, becoming east after midnight. Chance of rain 20 percent.

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Steffan Reservoir Temperature Statistics

September Temperature

Yankton, Chan Gurney Municipal Airport (11.2 miles)

  • Lowest 13 September, 2026

    48.9 °F

  • Average September

    69 °F

  • Highest 4 September, 2026

    95 °F

Climate (2021–2026)

Yankton, Chan Gurney Municipal Airport (11.2 miles)

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  • Average Low 2021–2026

    39.4 °F

  • Average 2021–2026

    50.5 °F

  • Average High 2021–2026

    61.8 °F
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