Grand Coulee Weather Forecast

    • 47
    • 62

    Rain Showers

    • 52
    • 71

    Partly Sunny

    • 52
    • 70

    Partly Sunny

    • 53
    • 76

    Mostly Sunny

    • 55
    • 79

    Mostly Sunny

    • 55
    • 82

    Mostly Sunny

Today 13 Sep Upper Columbia Basin

Rain Showers. Highs in the upper 50s to lower 60s. South wind 5 to 15 Mph with Gusts up to 30 Mph. Chance of precipitation near 100 percent. Rainfall Amounts up to a half inch possible.

Tonight 13 Sep Upper Columbia Basin

Cloudy with rain Showers likely in the Evening, then partly cloudy overnight. Lows in the mid to upper 40s. Southwest wind 5 to 15 Mph. Gusts up to 25 Mph in the evening. Chance of precipitation 70 percent. Rainfall Amounts less than a tenth of an inch.

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Grand Coulee Temperature Statistics

September Temperature

Omak Airport (42.9 miles)

  • Lowest 6 September, 2026

    46.7 °F

  • Average September

    64.6 °F

  • Highest 10 September, 2026

    85.6 °F

Climate (2021–2026)

Omak Airport (42.9 miles)

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  • Average Low 2021–2026

    40.7 °F

  • Average 2021–2026

    51.8 °F

  • Average High 2021–2026

    62.9 °F
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