Lake Merwin Weather Forecast

    • 56
    • 70

    Rain Showers Likely

    • 55
    • 62

    Rain Showers Likely

    • 56
    • 63

    Chance Rain Showers

    • 55
    • 62

    Chance Rain Showers

    • 57
    • 68

    Mostly Cloudy

    • 58
    • 69

    Rain Showers Likely

    • 55
    • 64

    Rain Showers Likely

Today 8 Sep South Washington Cascade Foothills

Partly sunny this Morning, then mostly cloudy with a chance of Showers with a slight chance of Thunderstorms this afternoon. Highs in the mid 70s. Winds light. Chance of rain 50 percent. Rainfall Amounts less than a tenth of an Inch, except higher Amounts possible in Thunderstorms.

Tonight 8 Sep South Washington Cascade Foothills

A slight chance of Thunderstorms in the evening. Showers likely. Lows in the mid 50s. Winds light. Chance of rain 70 percent. Rainfall Amounts a tenth to a quarter of an Inch, except higher Amounts possible in Thunderstorms.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Lake Merwin Temperature Statistics

September Temperature

Southwest Washington Regional Airport (22.4 miles)

  • Lowest 2 September, 2025

    55.9 °F

  • Average September

    66.8 °F

  • Highest 2 September, 2025

    88 °F

Climate (2020–Present)

Southwest Washington Regional Airport (22.4 miles)

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2020–2025

    45 °F

  • Average 2020–2025

    52.8 °F

  • Average High 2020–2025

    62.3 °F
Get WillyWeather+ to remove ads