Lewistown Weather Forecast

    • 48
    • 68

    Chance Thunderstorms

    • 47
    • 77

    Partly Sunny

    • 48
    • 73

    Chance Rain Showers

    • 46
    • 68

    Rain Showers Likely

    • 47
    • 75

    Mostly Sunny

    • 46
    • 74

    Partly Sunny

Today 13 Sep Fergus County below 4500ft

Cloudy. Patchy fog in the morning. Slight chance of Thunderstorms in the Morning, then chance of rain Showers and slight chance of Thunderstorms in the afternoon. Highs 65 to 75. Southwest Winds up to 5 Mph shifting to the southeast in the afternoon. Chance of precipitation 50 percent.

Tonight 13 Sep Fergus County below 4500ft

Mostly cloudy with a 20 percent chance of rain Showers in the Evening, then partly cloudy after midnight. Lows 50 to 55. South Winds up to 10 Mph.

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Lewistown Temperature Statistics

September Temperature

Lewistown, Lewistown Municipal Airport (1.2 miles)

  • Lowest 5 September, 2025

    34 °F

  • Average September

    62.5 °F

  • Highest 2 September, 2025

    86 °F

Climate (2020–Present)

Lewistown, Lewistown Municipal Airport (1.2 miles)

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  • Average Low 2020–2025

    32.3 °F

  • Average 2020–2025

    44.4 °F

  • Average High 2020–2025

    56.3 °F
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