Rock Island Lakes Weather Forecast

    • 45
    • 64

    Decreasing Clouds

    • 48
    • 70

    Mostly Sunny

    • 48
    • 76

    Mostly Sunny

    • 43
    • 74

    Mostly Sunny

    • 43
    • 72

    Mostly Sunny

    • 44
    • 71

    Mostly Sunny

Today 17 Aug Northwest Beaverhead County

Mostly cloudy. A 50 percent chance of Thunderstorms in the afternoon. Highs 65 to 75. Southwest Winds 5 to 15 Mph.

Tonight 17 Aug Northwest Beaverhead County

Mostly cloudy with a 20 percent chance of Thunderstorms in the Evening, then mostly clear after midnight. Lows 45 to 50. South Winds up to 10 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Rock Island Lakes Temperature Statistics

August Temperature

Salmon, Lemhi County Airport (15.5 miles)

  • Lowest 8 August, 2025

    42.7 °F

  • Average August

    67.1 °F

  • Highest 12 August, 2025

    95.6 °F

Climate (2020–Present)

Salmon, Lemhi County Airport (15.5 miles)

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  • Average Low 2020–2025

    32.2 °F

  • Average 2020–2025

    45.3 °F

  • Average High 2020–2025

    58.2 °F
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