Alton Weather Forecast

    • 52
    • 66

    Mostly Sunny

    • 51
    • 65

    Increasing Clouds

    • 51
    • 67

    Mostly Cloudy

    • 49
    • 68

    Partly Sunny

    • 47
    • 61

    Chance Rain

    • 47
    • 57

    Slight Chance Rain

    • 47
    • 60

    Partly Sunny

Today 21 May Northern Humboldt Coast

Mostly cloudy early in the morning then becoming mostly sunny. Patchy fog in the morning. Highs 60 to 74. West wind around 10 Mph.

Tonight 21 May Northern Humboldt Coast

Partly cloudy. Patchy fog overnight. Lows 47 to 57. West wind around 10 Mph.

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Alton Temperature Statistics

May Temperature

Fortuna Rohnerville Airport (0.6 miles)

  • Lowest 18 May, 2026

    39.2 °F

  • Average May

    52.5 °F

  • Highest 12 May, 2026

    66.2 °F

Climate (2021–Present)

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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