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National Weather Service Forecast for: St. Charles County
Issued by: NWS National Weather Service Saint Louis, MO
Updated: 914 PM CDT Sat Jun 27 2026
St. Charles , MO
 
Tonight


Thunder storm
Thunder storm
Sunday


Fog a.m.
Fog a.m.
Sunday
Night

Partly Cloudy
Partly Cloudy
Monday


Hot
Hot
Monday
Night

Mostly Clear
Mostly Clear
Tuesday


Hot
Hot
Tuesday
Night

Hot
Hot
Wednesday


Hot
Hot
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 ≈95°F Lo ≈75°F

 

Tonight
 
Partly cloudy. A slight chance of showers and thunderstorms this evening, then a chance of showers and thunderstorms after midnight. Patchy fog after midnight. Lows in the lower 70s. South winds around 5 mph. Chance of rain 30 percent.
Sunday
 
Patchy fog in the morning. Sunny with highs in the lower 90s. South winds 5 to 10 mph. Heat index values up to 106 in the afternoon.
Sunday Night
 
Clear in the evening, then becoming partly cloudy. Humid with lows in the mid 70s. South winds 5 to 10 mph. Heat index values up to 107 early in the evening.
Monday
 
Mostly sunny. Hot with highs in the mid 90s. South winds 5 to 10 mph. Heat index values up to 111.
Monday Night
 
Mostly clear. Humid with lows in the mid 70s. South winds 5 to 10 mph. Heat index values up to 110 early in the evening.
Tuesday
 
Clear, hot. Highs in the mid 90s.
Tuesday Night
 
Clear, hot. Lows in the mid 70s.
Wednesday
 
Clear, hot. Highs in the mid 90s.
Wednesday Night
 
Mostly clear. Lows in the mid 70s. Heat index values up to 110 early in the evening.
Thursday
 
Sunny. A slight chance of showers and thunderstorms in the afternoon. Highs in the mid 90s. Chance of rain 20 percent. Heat index values up to 105.
Thursday Night
 
Partly cloudy in the evening, then becoming mostly clear. Lows in the mid 70s. Heat index values up to 105 early in the evening.
Zone Forecast
 
St. Charles County

 

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