Lake Armstrong Weather Forecast

    • 55
    • 78

    Mostly Cloudy

    • 51
    • 73

    Increasing Clouds

    • 52
    • 70

    Mostly Cloudy

    • 51
    • 71

    Chance Rain

    • 51
    • 71

    Partly Sunny

    • 50
    • 72

    Partly Sunny

    • 51
    • 73

    Partly Sunny

Today 9 Sep Lowlands of Western Skagit and Northwestern Snohomish Counties

Mostly sunny. Patchy fog in the morning. Highs in the upper 60s to mid 70s. Light wind becoming northwest to 10 Mph in the afternoon.

Tonight 9 Sep Lowlands of Western Skagit and Northwestern Snohomish Counties

Mostly cloudy. Lows in the 50s. Northwest wind to 10 Mph becoming south with Gusts to 20 Mph after midnight.

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Lake Armstrong Temperature Statistics

September Temperature

Arlington Municipal Airport (4.3 miles)

  • Lowest 6 September, 2026

    46.9 °F

  • Average September

    60.2 °F

  • Highest 4 September, 2026

    73 °F

Climate (2021–2026)

Arlington Municipal Airport (4.3 miles)

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  • Average Low 2021–2026

    42.6 °F

  • Average 2021–2026

    50.9 °F

  • Average High 2021–2026

    59.9 °F
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