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National Weather Service Forecast for: St. Charles County
Issued by: NWS National Weather Service Saint Louis, MO
Updated: 853 PM CDT Sat Jul 25 2026
St. Charles , MO
 
Tonight


Partly Cloudy
Partly Cloudy
Sunday


Thunder storm
Thunder storm
Sunday
Night

Thunder storm
Thunder storm
Monday


Hot
Hot
Monday
Night

Mostly Clear
Mostly Clear
Tuesday


Sunny
Sunny
Tuesday
Night

Partly Cloudy
Partly Cloudy
Wednesday


Mostly Clear
Mostly Clear
Wednesday
Night

Mostly Clear
Mostly Clear
Lo ≈75°F Hi ≈95°F Lo ≈75°F Hi ≈95°F Lo ≈75°F Hi ≈95°F Lo ≈75°F Hi ≈85°F Lo ≈65°F

 

Tonight
 
Mostly clear this evening, then becoming partly cloudy. Lows in the mid 70s. South winds around 5 mph this evening, becoming light and variable. Heat index values up to 106 early this evening.
Sunday
 
Partly sunny. A chance of showers and thunderstorms, mainly in the morning. Humid with highs in the mid 90s. Southwest winds around 5 mph. Chance of rain 30 percent. Heat index values up to 108.
Sunday Night
 
Partly cloudy. A slight chance of showers and thunderstorms after midnight. Humid with lows in the upper 70s. Southwest winds around 5 mph. Chance of rain 20 percent. Heat index values up to 108 early in the evening.
Monday
 
Sunny, hot with highs in the upper 90s. Southwest winds 5 to 10 mph. Heat index values up to 112.
Monday Night
 
Mostly clear. Humid with lows in the upper 70s. Southwest winds 5 to 10 mph. Heat index values up to 111 early in the evening.
Tuesday
 
Sunny. Highs in the lower 90s. Heat index values up to 105.
Tuesday Night
 
Partly cloudy in the evening, then clearing. Lows in the lower 70s. Heat index values up to 100 early in the evening.
Wednesday
 
Mostly clear. Highs in the upper 80s.
Wednesday Night
 
Mostly clear. Lows in the upper 60s.
Thursday
 
Mostly clear. Highs in the upper 80s.
Thursday Night
 
Partly cloudy. A slight chance of showers and thunderstorms after midnight. Lows in the upper 60s. Chance of rain 20 percent.
Friday
 
Partly sunny with a slight chance of showers. A slight chance of thunderstorms in the afternoon. Highs in the upper 80s. Chance of rain 20 percent.
Friday Night
 
Partly cloudy. A slight chance of showers and thunderstorms. Lows around 70.
Saturday
 
Partly cloudy. A slight chance of showers and thunderstorms. Highs in the upper 80s.
Zone Forecast
 
St. Charles County

 

Forecast from NOAA-NWS for St. Charles County. (Zone forecast)