Alton Weather Forecast

    • 56
    • 77

    Rain Showers

    • 50
    • 70

    Mostly Cloudy

    • 56
    • 72

    Rain Showers Likely

    • 58
    • 72

    Chance Thunderstorms

    • 60
    • 80

    Chance Rain Showers

    • 63
    • 83

    Chance Rain Showers

Today 19 May Madison

Mostly cloudy with a chance of Thunderstorms. Showers, mainly this morning. Some Thunderstorms may produce heavy rainfall. Highs in the upper 70s. South Winds 5 to 10 Mph, becoming southwest 10 to 15 Mph this afternoon. Chance of rain 90 percent.

Tonight 19 May Madison

Cloudy with a chance of Showers. A chance of Thunderstorms, mainly in the evening. Lows in the mid 50s. North Winds 5 to 10 Mph. Chance of rain 50 percent.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Alton Temperature Statistics

May Temperature

St. Louis Regional Airport (8.1 miles)

  • Lowest 7 May, 2026

    39.6 °F

  • Average May

    59.1 °F

  • Highest 15 May, 2026

    82.4 °F

Climate (2021–Present)

St. Louis Regional Airport (8.1 miles)

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2021–2026

    46.5 °F

  • Average 2021–2026

    54.5 °F

  • Average High 2021–2026

    66.7 °F
Get WillyWeather+ to remove ads