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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)