Grass Valley Reservoir Weather Forecast

    • 63
    • 85

    Rain Showers

    • 62
    • 81

    Rain Showers Likely

    • 59
    • 80

    Rain Showers Likely

    • 55
    • 69

    Rain Showers

    • 56
    • 72

    Rain Showers Likely

    • 56
    • 73

    Chance Thunderstorms

    • 56
    • 75

    Slight Chance Thunderstorms

Today 23 Aug Southern Mountains

Partly cloudy with isolated Showers and Thunderstorms in the Morning, then mostly cloudy with rain Showers and scattered Thunderstorms in the afternoon. Highs in the mid 70s. Chance of precipitation 80 percent.

Tonight 23 Aug Southern Mountains

Mostly cloudy. Rain Showers likely and a chance of Thunderstorms in the Evening, then a chance of rain Showers and a slight chance of Thunderstorms after midnight. Lows in the mid 50s. Chance of precipitation 70 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Grass Valley Reservoir Temperature Statistics

August Temperature

St George Municipal Airport (25.5 miles)

  • Lowest 3 August, 2025

    70 °F

  • Average August

    90.1 °F

  • Highest 7 August, 2025

    107.1 °F

Climate (2020–Present)

St George Municipal Airport (25.5 miles)

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  • Average Low 2020–2025

    52.2 °F

  • Average 2020–2025

    64.3 °F

  • Average High 2020–2025

    76.5 °F
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