Lake Merwin Weather Forecast

    • 51
    • 73

    Increasing Clouds

    • 50
    • 69

    Partly Sunny

    • 54
    • 66

    Mostly Cloudy

    • 55
    • 69

    Partly Sunny

    • 58
    • 75

    Mostly Sunny

    • 57
    • 80

    Mostly Sunny

Today 18 Jul South Washington Cascade Foothills

Mostly sunny. Highs around 80. West wind 5 to 10 Mph.

Tonight 18 Jul South Washington Cascade Foothills

Partly cloudy. Lows around 50. Northwest wind 5 to 10 Mph.

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Lake Merwin Temperature Statistics

July Temperature

Southwest Washington Regional Airport (22.4 miles)

  • Lowest 5 July, 2025

    48 °F

  • Average July

    67.3 °F

  • Highest 13 July, 2025

    95 °F

Climate (2020–Present)

Southwest Washington Regional Airport (22.4 miles)

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  • Average Low 2020–2025

    45 °F

  • Average 2020–2025

    52.8 °F

  • Average High 2020–2025

    62.3 °F
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