Third Napa Slough Weather Forecast

    • 53
    • 82

    Partly Sunny

    • 53
    • 74

    Mostly Cloudy

    • 53
    • 76

    Mostly Sunny

    • 54
    • 80

    Mostly Sunny

    • 57
    • 89

    Mostly Sunny

    • 57
    • 88

    Partly Sunny

Today 19 Sep North Bay Interior Valleys

Partly cloudy in the morning then becoming sunny. Areas of fog in the morning. Highs in the mid 70s to upper 80s. Southwest Winds 5 to 15 Mph.

Tonight 19 Sep North Bay Interior Valleys

Partly cloudy in the evening then becoming mostly cloudy. Patchy fog after midnight. Lows in the 50s to lower 60s. Southwest Winds 5 to 10 Mph.

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Third Napa Slough Temperature Statistics

September Temperature

Napa, Napa County Airport (6.2 miles)

  • Lowest 6 September, 2026

    45.6 °F

  • Average September

    66.6 °F

  • Highest 9 September, 2026

    99.6 °F

Climate (2021–2026)

Napa, Napa County Airport (6.2 miles)

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  • Average Low 2021–2026

    47.3 °F

  • Average 2021–2026

    58.5 °F

  • Average High 2021–2026

    70.3 °F
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