| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 06-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 69°. Wind north around 4 mph, gusting to 22 mph. |
| Tuesday |
Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thundershowers possible. High 88°. Heat index up to 92°. UV index up to 8. Wind north around 5 mph, gusting to 25 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Low 68°. Wind northeast around 2 mph, gusting to 20 mph. |
| Wednesday |
Partly to mostly sunny. Patchy light fog in the morning. Hot. High 90°. Heat index up to 96°. UV index up to 8. Wind south-southwest around 2 mph, gusting to 21 mph. |
| Wednesday night |
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Light to moderate fog after midnight. Low 70°. Wind southeast around 4 mph, gusting to 17 mph, in the evening, becoming south after midnight. |
| Thursday |
Partly to mostly cloudy. Light to moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. Hot. High 93°. Heat index up to 100°. UV index up to 8. Wind southwest around 5 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Moderate fog. A chance of rain. Scattered thunderstorms likely. Low 75°. Wind west-southwest around 4 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Friday |
Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 91°. Heat index up to 101°. UV index up to 8. Wind west-southwest around 6 mph, gusting to 23 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Friday night |
Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Low 75°. Wind west-southwest around 3 mph, gusting to 19 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Saturday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 92°. Heat index up to 101°. UV index up to 8. Wind north-northeast around 3 mph, gusting to 23 mph. |
| Saturday night |
Partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 72°. Wind northeast around 4 mph, gusting to 22 mph. |
| Sunday |
Sunny. Patchy light fog in the morning. Hot. High 93°. Heat index up to 101°. UV index up to 9. Wind east-northeast around 3 mph, gusting to 21 mph, in the morning, becoming north in the afternoon. |
| Sunday night |
Clear. Patchy light fog after midnight. Low 71°. Wind northeast around 2 mph, gusting to 18 mph, in the evening, becoming southwest after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.