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National Weather Service Forecast for: St. Charles County
Issued by: NWS National Weather Service Saint Louis, MO

Updated: 239 AM CDT Sun Jun 28 2026

St. Charles , MO

Today Thunder storm	Tonight Partly Cloudy	Monday Hot	Monday Night Mostly Clear	Tuesday Hot	Tuesday Night Hot	Wednesday Hot	Wednesday Night Hot	Thursday Hot
Hi ≈95°F	Lo ≈75°F	Hi ≈95°F	Lo ≈75°F	Hi ≈95°F	Lo ≈75°F	Hi ≈95°F	Lo ≈75°F	Hi ≈95°F

Today	Sunny. A slight chance of showers and thunderstorms this morning. Patchy fog this morning. Highs in the lower 90s. South winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 109 this afternoon.
Tonight	Mostly 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 110 early in the evening.
Monday	Sunny, hot with highs in the mid 90s. South winds 10 to 15 mph. Heat index values up to 110.
Monday Night	Mostly clear. Humid with lows in the mid 70s. South winds 5 to 10 mph. Heat index values up to 108 early in the evening.
Tuesday	Sunny, hot with highs in the mid 90s. South winds 5 to 10 mph. Heat index values up to 112.
Tuesday Night	Clear, hot. Lows in the mid 70s.
Wednesday	Clear, hot. Highs in the mid 90s.
Wednesday Night	Mostly clear. Hot. Lows in the mid 70s.
Thursday	Mostly clear. Hot. Highs in the mid 90s.
Thursday Night	Mostly clear. Hot. Lows in the mid 70s.
Friday	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.
Friday 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.
Independence Day	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.
Zone Forecast	St. Charles County

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