Grinnell Lake Weather Forecast

    • 32
    • 56

    Breezy

    • 34
    • 58

    Mostly Sunny

    • 33
    • 57

    Mostly Sunny

    • 32
    • 55

    Mostly Sunny

    • 33
    • 55

    Mostly Sunny

    • 34
    • 58

    Mostly Sunny

    • 35
    • 58

    Mostly Sunny

Today 13 Sep Upper San Joaquin River

Sunny. Highs 55 to 69. Southwest Winds 5 to 15 Mph with Gusts to around 50 Mph.

Tonight 13 Sep Upper San Joaquin River

Clear. Lows 35 to 47. South Winds up to 10 Mph. Gusts up to 30 Mph in the evening.

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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

    60.1 °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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