Alton Weather Forecast

    • 49
    • 65

    Increasing Clouds

    • 51
    • 67

    Gradual Clearing

    • 53
    • 71

    Partly Sunny

    • 53
    • 70

    Partly Sunny

    • 51
    • 69

    Partly Sunny

    • 50
    • 66

    Partly Sunny

    • 51
    • 65

    Mostly Cloudy

Today 20 Jun Northern Coastal Humboldt

Mostly cloudy until early afternoon then becoming partly cloudy. Patchy fog in the morning. Highs 59 to 69. Northwest wind around 10 Mph.

Tonight 20 Jun Northern Coastal Humboldt

Partly cloudy early in the evening then becoming mostly cloudy. Patchy fog overnight. Lows 44 to 54. Northwest wind up to 10 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Alton Temperature Statistics

June Temperature

Fortuna Rohnerville Airport (0.6 miles)

  • Lowest 1 June, 2026

    42.8 °F

  • Average June

    54.8 °F

  • Highest 3 June, 2026

    69.8 °F

Climate (2021–2026)

Fortuna Rohnerville Airport (0.6 miles)

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  • Average Low 2021–2026

    45.3 °F

  • Average 2021–2026

    51.4 °F

  • Average High 2021–2026

    59.7 °F
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