| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
||||||||||||||||||||||||||||||||||||||||||||||||
| Updated: Sunday, 28-Jun-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
|
| Today |
Mostly sunny in the morning, becoming sunny in the afternoon. Hot. High 93°. Heat index up to 101°. UV index up to 9. Wind south around 5 mph, gusting to 26 mph, in the morning, becoming 9 mph, gusting to 26 mph, in the afternoon. |
| Tonight |
Fair in the evening, becoming partly cloudy after midnight. Low 71°. Wind south-southwest around 7 mph, gusting to 22 mph. |
| Monday |
Partly cloudy. Hot. High 96°. Heat index up to 104°. UV index up to 10. Wind south-southwest around 8 mph, gusting to 27 mph. |
| Monday night |
Fair to partly cloudy. Patchy light fog after midnight. Low 73°. Wind south-southwest around 7 mph, gusting to 23 mph. |
| Tuesday |
Sunny. Patchy light fog in the morning. Very hot. High 97°. Heat index up to 107°. UV index up to 9. Wind south-southwest around 8 mph, gusting to 26 mph. |
| Tuesday night |
Clear. Patchy light fog after midnight. Low 73°. Wind south-southwest around 5 mph, gusting to 21 mph. |
| Wednesday |
Sunny in the morning, becoming mostly sunny in the afternoon. Very hot. High 97°. Heat index up to 107°. UV index up to 9. Wind south-southwest around 6 mph, gusting to 25 mph. |
| Wednesday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. Low 73°. Wind south-southeast around 5 mph, gusting to 20 mph. |
| Thursday |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. A chance of rain in the afternoon. Scattered thunderstorms likely. Hot. High 95°. Heat index up to 105°. UV index up to 10. Wind south-southwest around 6 mph, gusting to 25 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Thursday night |
Partly cloudy. Moderate fog. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Low 76°. Wind south-southwest around 5 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Friday |
Mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Moderate fog in the morning. A slight chance of rain. Scattered thunderstorms likely, some possibly severe. Hot. High 93°. Heat index up to 104°. UV index up to 7. Wind south-southwest around 6 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Partly cloudy in the evening, becoming clear after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A slight chance of rain. Scattered thunderstorms likely. Low 75°. Wind south-southeast around 4 mph, gusting to 17 mph, in the evening, becoming southwest after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday |
Sunny in the morning, becoming mostly sunny in the afternoon. Moderate fog in the morning. Hot. High 95°. Heat index up to 106°. UV index up to 9. Wind southwest around 4 mph, gusting to 21 mph. |
| Saturday night |
Partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 74°. Wind east-southeast around 3 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.