Guerneville Weather Forecast

    • 52
    • 73

    Areas Fog

    • 54
    • 80

    Mostly Sunny

    • 53
    • 83

    Mostly Sunny

    • 52
    • 78

    Partly Sunny

    • 53
    • 78

    Mostly Sunny

    • 54
    • 80

    Mostly Sunny

Today 17 Sep North Bay Interior Valleys

Mostly cloudy in the morning then becoming partly cloudy. Patchy fog in the morning. A slight chance of drizzle in the morning. Highs in the mid 60s to upper 70s. South Winds 5 to 15 Mph.

Tonight 17 Sep North Bay Interior Valleys

Mostly clear in the evening then becoming partly cloudy. Patchy fog in the evening. Areas of fog after midnight. Lows in the 40s to upper 50s. West Winds 5 to 10 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Guerneville Temperature Statistics

September Temperature

Santa Rosa, Santa Rosa Sonoma County Airport (9.3 miles)

  • Lowest 5 September, 2026

    46.7 °F

  • Average September

    67.6 °F

  • Highest 10 September, 2026

    101.6 °F

Climate (2021–2026)

Santa Rosa, Santa Rosa Sonoma County Airport (9.3 miles)

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  • Average Low 2021–2026

    45.9 °F

  • Average 2021–2026

    58.7 °F

  • Average High 2021–2026

    72.9 °F
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