Newcastle Weather Forecast

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    Rain

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    • 47

    Rain

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    Rain Likely

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    Rain Likely

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    Mostly Cloudy

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    Mostly Cloudy

Today 23 Dec Foothills and Valleys of Central King County

Mostly cloudy. Highs in the mid to upper 40s. Light wind.

Tonight 23 Dec Foothills and Valleys of Central King County

Cloudy in the Evening, then a chance of rain after midnight. Cloudy with rain likely in the morning. Rainfall Amounts less than a tenth of an inch likely. Lows in the mid to upper 30s. Light wind becoming east to 10 Mph with Gusts to 30 Mph after midnight.

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Newcastle Temperature Statistics

December Temperature

Renton Municipal Airport (3.7 miles)

  • Lowest 1 December, 2025

    33.1 °F

  • Average December

    48.5 °F

  • Highest 15 December, 2025

    60.1 °F

Climate (2020–Present)

Renton Municipal Airport (3.7 miles)

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  • Average Low 2020–2025

    47.4 °F

  • Average 2020–2025

    54.6 °F

  • Average High 2020–2025

    62.3 °F
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