Issaquah Weather Forecast

    • 59
    • 89

    Sunny

    • 55
    • 80

    Mostly Sunny

    • 55
    • 74

    Partly Sunny

    • 56
    • 77

    Partly Sunny

    • 58
    • 72

    Chance Rain

    • 55
    • 71

    Chance Rain

    • 55
    • 73

    Chance Rain

Today 16 Sep Eastside

Sunny. Highs in the mid 80s to lower 90s. Northeast wind 10 to 15 Mph becoming southeast in the afternoon. Gusts to 30 Mph.

Tonight 16 Sep Eastside

Clear. Lows near 60. Southeast wind 10 to 15 Mph with Gusts to 30 Mph becoming south after midnight.

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Issaquah Temperature Statistics

September Temperature

Renton Municipal Airport (8.7 miles)

  • Lowest 10 September, 2025

    57 °F

  • Average September

    66.5 °F

  • Highest 3 September, 2025

    82.9 °F

Climate (2020–Present)

Renton Municipal Airport (8.7 miles)

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  • Average Low 2020–2025

    47.3 °F

  • Average 2020–2025

    54.5 °F

  • Average High 2020–2025

    62.2 °F
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