Grand Coulee Weather Forecast

    • 63
    • 91

    Decreasing Clouds

    • 63
    • 86

    Mostly Cloudy

    • 60
    • 78

    Rain Showers Likely

    • 59
    • 79

    Chance Rain Showers

    • 61
    • 83

    Partly Sunny

    • 61
    • 82

    Partly Sunny

Today 7 Sep Upper Columbia Basin

Mostly cloudy. A chance of rain Showers in the Morning, then a chance of Showers and Thunderstorms in the afternoon. Areas of smoke in the morning. Haze. Highs in the mid to upper 80s. South wind 5 to 15 Mph. Chance of precipitation 50 percent. Rainfall Amounts less than a tenth of an Inch, except higher Amounts possible in Thunderstorms.

Tonight 7 Sep Upper Columbia Basin

Partly cloudy. A chance of Showers and Thunderstorms in the evening. Haze. Areas of smoke overnight. Lows in the mid 50s to lower 60s. West wind 5 to 15 Mph. Chance of precipitation 20 percent.

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Grand Coulee Temperature Statistics

September Temperature

Omak Airport (42.9 miles)

  • Lowest 3 September, 2025

    64.9 °F

  • Average September

    83.5 °F

  • Highest 3 September, 2025

    104 °F

Climate (2020–Present)

Omak Airport (42.9 miles)

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  • Average Low 2020–2025

    40.6 °F

  • Average 2020–2025

    51.7 °F

  • Average High 2020–2025

    62.7 °F
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