| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
||||||||||||||||||||||||||||||||||||||||||||||||
| Updated: Saturday, 11-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
|
| Tonight |
Fair to partly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 72°. Wind north around 5 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Sunday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. High 86°. UV index up to 8. Wind north around 7 mph, gusting to 25 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Fair. Patchy light fog in the evening, then light to moderate fog after midnight. Low 69°. Wind north around 5 mph, gusting to 22 mph. |
| Monday |
Mostly sunny in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. High 89°. Heat index up to 95°. UV index up to 9. Wind north-northeast around 5 mph, gusting to 25 mph, in the morning, becoming 8 mph, gusting to 26 mph, in the afternoon. |
| Monday night |
Clear. Patchy light fog after midnight. Low 69°. Wind north-northeast around 3 mph, gusting to 22 mph. |
| Tuesday |
Sunny. Patchy light fog in the morning. Hot. High 91°. Heat index up to 97°. UV index up to 9. Wind north-northeast around 5 mph, gusting to 25 mph. |
| Tuesday night |
Clear. Patchy light fog after midnight. Low 69°. Wind east-northeast around 2 mph, gusting to 20 mph. |
| Wednesday |
Sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 92°. Heat index up to 98°. UV index up to 9. Wind northeast around 3 mph, gusting to 22 mph. |
| Wednesday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Low 70°. Wind east around 2 mph, gusting to 16 mph, in the evening, becoming southwest after midnight. |
| Thursday |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 93°. Heat index up to 100°. UV index up to 9. Wind west around 2 mph, gusting to 21 mph, in the morning, becoming east-southeast in the afternoon. |
| Thursday night |
Mostly clear. Light to moderate fog after midnight. Low 71°. Wind south-southwest around 2 mph. |
| Friday |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thundershowers possible. High 89°. Heat index up to 97°. UV index up to 8. Wind west-southwest around 6 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Friday night |
Mostly clear. Patchy light fog in the evening, then light to moderate fog after midnight. Low 73°. Wind west-southwest around 4 mph, gusting to 17 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.