| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
||||||||||||||||||||||||||||||||||||||||||||||||
| Updated: Tuesday, 21-Jul-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
|
| Today |
Partly cloudy. A chance of rain in the morning, then a slight chance of rain in the afternoon. Hot. High 92°. Heat index up to 102°. UV index up to 8. Wind northwest around 9 mph, gusting to 26 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Tonight |
Fair to partly cloudy in the evening, becoming fair after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain. Low 70°. Wind north around 7 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday |
Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. High 83°. UV index up to 7. Wind north around 6 mph, gusting to 25 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Wednesday night |
Partly to mostly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. A chance of rain. Relatively cool. Low 64°. Wind northeast around 5 mph, gusting to 21 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. High 83°. UV index up to 8. Wind east-northeast around 5 mph, gusting to 24 mph. |
| Thursday night |
Partly cloudy. Relatively cool. Low 63°. Wind east-northeast around 5 mph, gusting to 22 mph. |
| Friday |
Mostly cloudy to cloudy in the morning, becoming cloudy in the afternoon. Rain likely. Relatively cool. High 78°. UV index up to 6. Wind east-southeast around 4 mph, gusting to 22 mph. Chance of precipitation 60 percent. Precipitation mostly between a quarter and half an inch. |
| Friday night |
Mostly cloudy to cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog after midnight. A slight chance of rain. Relatively cool. Low 67°. Wind east-southeast around 4 mph, gusting to 18 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday |
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 91°. Heat index up to 95°. UV index up to 9. Wind southeast around 4 mph, gusting to 23 mph. |
| Saturday night |
Mostly clear in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 70°. Wind east-southeast around 3 mph, gusting to 18 mph, in the evening, becoming south-southeast after midnight. |
| Sunday |
Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Hot. High 94°. Heat index up to 101°. UV index up to 8. Wind south-southeast around 4 mph, gusting to 20 mph. |
| Sunday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 73°. Wind south-southwest around 4 mph in the evening, becoming 8 mph after midnight. |
| Monday |
Partly cloudy in the morning, becoming sunny in the afternoon. Breezy and very hot. High 100°. Heat index up to 109°. UV index up to 9. Wind west-southwest around 13 mph, gusting to 29 mph. |
| Monday night |
Clear. Patchy light fog after midnight. Low 72°. Wind west-northwest around 6 mph, gusting to 22 mph, in the evening, becoming north-northwest after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.