Grinnell Lake Weather Forecast

    • 36
    • 57

    Mostly Sunny

    • 35
    • 55

    Partly Sunny

    • 32
    • 52

    Partly Sunny

    • 31
    • 53

    Mostly Sunny

    • 27
    • 50

    Mostly Sunny

Today 23 Sep Upper San Joaquin River

Warmer, sunny. Highs 57 to 73. Southeast Winds up to 10 Mph shifting to the southwest in the afternoon.

Tonight 23 Sep Upper San Joaquin River

Mostly clear. Lows 40 to 52. West Winds up to 5 Mph with Gusts to around 25 Mph shifting to the east 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 18 September, 2026

    28.4 °F

  • Average September

    58.7 °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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