Newcastle Weather Forecast

    • 56
    • 81

    Decreasing Clouds

    • 55
    • 77

    Mostly Sunny

    • 56
    • 77

    Mostly Sunny

    • 57
    • 77

    Partly Sunny

    • 57
    • 75

    Partly Sunny

    • 59
    • 80

    Mostly Sunny

Today 8 Aug Foothills and Valleys of Central King County

Partly sunny until late afternoon then becoming sunny. Highs in the lower to mid 80s. Light wind.

Tonight 8 Aug Foothills and Valleys of Central King County

Mostly clear. Lows in the 50s. Light wind.

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Newcastle Temperature Statistics

August Temperature

Renton Municipal Airport (3.7 miles)

  • Lowest 3 August, 2026

    52 °F

  • Average August

    68.1 °F

  • Highest 6 August, 2026

    87.1 °F

Climate (2021–2026)

Renton Municipal Airport (3.7 miles)

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  • Average Low 2021–2026

    47.4 °F

  • Average 2021–2026

    54.7 °F

  • Average High 2021–2026

    62.2 °F
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