Grinnell Lake Weather Forecast

    • 29
    • 51

    Mostly Sunny

    • 32
    • 53

    Mostly Sunny

    • 36
    • 56

    Mostly Sunny

    • 36
    • 55

    Partly Sunny

    • 35
    • 54

    Partly Sunny

    • 35
    • 55

    Mostly Sunny

Today 17 Sep Upper San Joaquin River

Sunny. Highs 49 to 63. Southwest Winds 5 to 15 Mph with Gusts to around 40 Mph.

Tonight 17 Sep Upper San Joaquin River

Mostly clear. Lows 31 to 43. Southwest Winds up to 10 Mph with Gusts to around 30 Mph shifting to the southeast after midnight.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Grinnell Lake Temperature Statistics

September Temperature

Mammoth Yosemite Airport (10.6 miles)

  • Lowest 5 September, 2026

    33.8 °F

  • Average September

    60.5 °F

  • Highest 9 September, 2026

    84.2 °F

Climate (2021–2026)

Mammoth Yosemite Airport (10.6 miles)

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  • Average Low 2021–2026

    29.4 °F

  • Average 2021–2026

    45.7 °F

  • Average High 2021–2026

    60.5 °F
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