Illinois · NWS LSX office

Alton, IL weather

It is 49°F and clear at St. Louis Regional Airport as of Oct 28, 3:55 AM CDT. Overnight: Mostly Clear, low near 52°F. Forecast from the National Weather Service, issued Oct 28, 1:26 AM CDT.

Updated Oct 28, 4:27 AM CDT (snapshot)

Current conditions

Temperature

49°F

Clear

Wind

Calm

Humidity 89%

Pressure · visibility

—

Visibility 10 mi

Observed at St. Louis Regional Airport (KALN), Oct 28, 3:55 AM CDT. Station readings can lag or be missing.

Alerts for this area

No active NWS alerts cover the Alton forecast zone right now.

Around the NWS LSX forecast area

No active alerts in zones served by the LSX office near Alton.

From the alert snapshot of Oct 28, 2026, 5:12 AM EDT. No alerts are active anywhere in Illinois.

For official warnings, check weather.gov and your local authorities. OpenForecast repeats National Weather Service alerts and may be delayed or incomplete. Follow instructions from emergency officials.

Next 24 hours

Hourly forecast for Alton (local time)
TimeTempForecastPrecip. chanceWind
Wed 6 AM52°FMostly Sunny0%SE 2 mph
Wed 7 AM52°FMostly Sunny0%SE 3 mph
Wed 8 AM53°FMostly Sunny0%SE 5 mph
Wed 9 AM59°FSunny0%SE 6 mph
Wed 10 AM64°FSunny0%S 6 mph
Wed 11 AM69°FSunny0%S 7 mph
Wed 12 PM72°FSunny1%S 8 mph
Wed 1 PM75°FSunny1%S 9 mph
Wed 2 PM77°FSunny1%S 9 mph
Wed 3 PM78°FSunny0%S 10 mph
Wed 4 PM78°FSunny0%S 10 mph
Wed 5 PM76°FSunny0%S 9 mph
Wed 6 PM73°FMostly Clear0%S 8 mph
Wed 7 PM67°FMostly Clear1%SE 8 mph
Wed 8 PM66°FClear1%S 8 mph
Wed 9 PM64°FClear1%S 8 mph
Wed 10 PM63°FClear1%S 7 mph
Wed 11 PM61°FClear1%S 6 mph
Thu 12 AM60°FMostly Clear1%S 6 mph
Thu 1 AM59°FMostly Clear1%S 5 mph
Thu 2 AM58°FMostly Clear1%S 5 mph
Thu 3 AM57°FMostly Clear1%S 5 mph
Thu 4 AM57°FMostly Clear1%S 5 mph
Thu 5 AM56°FMostly Clear1%S 5 mph

Hourly values come from the NWS gridded forecast for the 2.5 km grid square that covers the city's center point. Conditions elsewhere in Alton can differ.

7-day forecast

Overnight

Low 52°F

Mostly clear, with a low around 52. Southeast wind around 2 mph.

Wednesday

High 78°F·Low 55°F

Sunny, with a high near 78. South wind 2 to 10 mph.

Wednesday Night: Mostly clear, with a low around 55. South wind 5 to 8 mph.

Thursday

High 82°F·Low 58°F

Sunny, with a high near 82. Southwest wind around 7 mph.

Thursday Night: Partly cloudy, with a low around 58. Northeast wind around 3 mph.

Friday

High 79°F·Low 57°F

Partly sunny, with a high near 79.

Friday Night: Mostly cloudy, with a low around 57.

Saturday

High 74°F·Low 55°F

A slight chance of rain showers after 1pm. Mostly cloudy, with a high near 74. Chance of precipitation is 20%.

Saturday Night: A chance of rain showers. Mostly cloudy, with a low around 55. Chance of precipitation is 50%.

Sunday

High 71°F·Low 55°F

A chance of rain showers. Mostly cloudy, with a high near 71. Chance of precipitation is 40%.

Sunday Night: A slight chance of rain showers after midnight. Mostly cloudy, with a low around 55. Chance of precipitation is 20%.

Monday

High 71°F·Low 56°F

A chance of rain showers. Mostly cloudy, with a high near 71. Chance of precipitation is 50%.

Monday Night: Rain showers likely. Mostly cloudy, with a low around 56. Chance of precipitation is 60%.

Tuesday

High 72°F

Rain showers likely. Mostly cloudy, with a high near 72. Chance of precipitation is 70%.

Nearby cities

Larger cities in the area

Other cities in Madison County

See every city we cover in Illinois, or check all active alerts.

About this forecast

Forecast office
Alton is served by the National Weather Service LSX forecast office, forecast zone ILZ100, county zone ILC119.
Location used
The Census Bureau's internal point for Alton (38.9039, -90.1512), in Madison County. Population: 24,967 (2024 estimate), number 89 of the 121 Illinois cities on this site.
Radar
Nearest NWS radar: KLSX. View it on radar.weather.gov.

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Sources

  • Forecast, hourly forecast, observations and alerts: National Weather Service API, api.weather.gov/points/38.9039,-90.1512 (forecast issued Oct 28, 1:26 AM CDT).
  • Official forecast page: forecast.weather.gov.
  • City location and population: U.S. Census Bureau, Vintage 2024 population estimates and 2024 Gazetteer files.
  • Snapshot taken Oct 28, 2026. The NWS and Census Bureau do not endorse OpenForecast.

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