| National Weather Service Forecast for:
St. Charles County Issued by: NWS National Weather Service Saint Louis, MO |
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| Updated: 1133 AM CDT Wed Aug 5 2026 | ||||||||||||||||||
| St. Charles , MO | ||||||||||||||||||
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| This Afternoon |
Mostly sunny with a slight chance of showers and thunderstorms. Highs around 90. South winds around 5 mph. Chance of rain 20 percent. |
| Tonight |
Mostly cloudy. A chance of showers and thunderstorms in the evening, then showers with thunderstorms likely after midnight. Some thunderstorms may produce heavy rainfall. Lows in the lower 70s. Southeast winds around 5 mph. Chance of rain 90 percent. |
| Thursday |
Mostly cloudy. Showers with thunderstorms likely in the morning, then a chance of showers and thunderstorms in the afternoon. Some thunderstorms may produce heavy rainfall in the morning. Highs in the mid 80s. South winds around 5 mph. Chance of rain 80 percent. |
| Thursday Night |
Mostly cloudy with a chance of showers and thunderstorms. Humid with lows in the lower 70s. Southeast winds around 5 mph. Chance of rain 50 percent. |
| Friday |
Partly sunny with a chance of showers and thunderstorms. Humid with highs in the upper 80s. Southwest winds around 5 mph. Chance of rain 50 percent. |
| Friday Night |
Partly cloudy with a chance of showers and thunderstorms. Lows in the lower 70s. Chance of rain 50 percent. |
| Saturday |
Mostly sunny. Highs around 90. Heat index values up to 100. |
| Saturday Night |
Mostly clear. Lows in the mid 70s. |
| Sunday |
Mostly clear. Highs in the mid 90s. |
| Sunday Night |
Mostly clear. Lows in the mid 70s. |
| Monday |
Mostly clear. Highs in the mid 90s. |
| Monday Night |
Mostly clear. A slight chance of showers and thunderstorms in the evening. Lows in the mid 70s. Chance of rain 20 percent. Heat index values up to 105 early in the evening. |
| Tuesday |
Mostly sunny. A slight chance of showers and thunderstorms in the afternoon. Highs in the lower 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)