| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
||||||||||||||||||||||||||||||||||||||||||||||||
| Updated: Sunday, 05-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
|
| Tonight |
Fair to partly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog. A chance of rain. Thunderstorms very likely, some possibly severe. Relatively cool. Low 67°. Wind north around 4 mph, gusting to 17 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thunderstorms likely. High 86°. UV index up to 7. Wind north around 6 mph, gusting to 24 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Monday night |
Mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 69°. Wind north around 4 mph, gusting to 21 mph. |
| Tuesday |
Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. A chance of rain. Scattered thunderstorms likely. High 86°. UV index up to 6. Wind north-northeast around 4 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. A chance of rain. Scattered thundershowers possible. Relatively cool. Low 67°. Wind northeast around 3 mph, gusting to 20 mph, in the evening, becoming east-southeast after midnight. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday |
Partly to mostly sunny. Patchy light fog in the morning. A chance of rain. Scattered thunderstorms likely. Hot. High 92°. Heat index up to 97°. UV index up to 9. Wind southeast around 3 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday night |
Fair in the evening, becoming partly cloudy after midnight. Low 68°. Wind south around 4 mph, gusting to 19 mph. |
| Thursday |
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. A chance of rain. Thunderstorms very likely, some possibly severe. Hot. High 93°. Heat index up to 98°. UV index up to 8. Wind southwest around 6 mph, gusting to 24 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog after midnight. A chance of rain in the evening, then rain likely after midnight. Thunderstorms very likely, some possibly severe. Low 73°. Wind south-southwest around 4 mph, gusting to 18 mph, in the evening, becoming west-southwest after midnight. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch. |
| Friday |
Cloudy in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning. Rain likely in the morning, then a chance of rain in the afternoon. Thunderstorms very likely, some possibly severe. High 87°. Heat index up to 94°. UV index up to 7. Wind southwest around 5 mph, gusting to 20 mph. Chance of precipitation 90 percent. Precipitation mostly around half an inch. |
| Friday night |
Partly cloudy. Moderate fog. Rain likely in the evening, then a chance of rain after midnight. Scattered thunderstorms likely. Low 73°. Wind west-southwest around 3 mph, gusting to 16 mph, in the evening, becoming north after midnight. Chance of precipitation 80 percent. Precipitation mostly between a quarter and half an inch. |
| Saturday |
Mostly sunny. Moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 91°. Heat index up to 99°. UV index up to 10. Wind west around 9 mph, gusting to 27 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog after midnight. Low 74°. Wind west around 7 mph, gusting to 25 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.