Sullivan Lake Weather Forecast

    • 36
    • 61

    Mostly Sunny

    • 35
    • 63

    Partly Sunny

    • 43
    • 61

    Mostly Cloudy

    • 40
    • 62

    Rain Likely

    • 37
    • 57

    Rain Likely

    • 29
    • 54

    Chance Rain

Today 21 Oct Upper Columbia Basin

Mostly sunny. Highs in the upper 50s to lower 60s. Southeast wind 5 to 10 Mph.

Tonight 21 Oct Upper Columbia Basin

Mostly clear. Lows in the mid to upper 30s. Northeast wind 5 to 10 Mph.

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Sullivan Lake Temperature Statistics

October Temperature

Grant County Airport (28 miles)

  • Lowest 16 October, 2025

    28 °F

  • Average October

    52.4 °F

  • Highest 8 October, 2025

    73 °F

Climate (2020–Present)

Grant County Airport (28 miles)

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  • Average Low 2020–2025

    40.9 °F

  • Average 2020–2025

    52.7 °F

  • Average High 2020–2025

    64.2 °F
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