| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
||||||||||||||||||||||||||||||||||||||||||||||||
| Updated: Sunday, 06-Sep-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
|
| Today |
Sunny in the morning, becoming mostly sunny in the afternoon. Very hot. High 97°. Heat index up to 102°. UV index up to 8. Wind east-northeast around 6 mph, gusting to 27 mph. |
| Tonight |
Fair in the evening, becoming fair to partly cloudy after midnight. Low 71°. Wind east-northeast around 5 mph, gusting to 23 mph. |
| Monday |
Sunny. Very hot. High 92°. UV index up to 8. Wind east-northeast around 5 mph, gusting to 26 mph. |
| Monday night |
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Low 66°. Wind east-northeast around 4 mph, gusting to 21 mph, in the evening, becoming east-southeast after midnight. |
| Tuesday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Very hot. High 95°. UV index up to 7. Wind south-southeast around 4 mph, gusting to 24 mph. |
| Tuesday night |
Fair in the evening, becoming clear after midnight. Low 68°. Wind south-southeast around 6 mph, gusting to 18 mph. |
| Wednesday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 97°. Heat index up to 102°. UV index up to 7. Wind west-southwest around 6 mph, gusting to 23 mph. |
| Wednesday night |
Mostly cloudy to cloudy in the evening, becoming dense overcast after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain in the evening, then rain likely after midnight. Precipitation showery or intermittent. Low 71°. Wind west-northwest around 5 mph, gusting to 16 mph, in the evening, becoming near calm after midnight. Chance of precipitation 80 percent. Precipitation mostly between half an inch and one inch. |
| Thursday |
Mostly cloudy to cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Precipitation showery or intermittent. Warm. High 84°. UV index up to 5. Wind northwest around 4 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. Low 66°. Wind north-northeast around 2 mph, gusting to 18 mph, in the evening, becoming southeast after midnight. |
| Friday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. Hot. High 86°. UV index up to 7. Wind south around 5 mph, gusting to 21 mph. |
| Friday night |
Mostly clear in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 69°. Wind south-southeast around 6 mph. |
| Saturday |
Partly to mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Very hot. High 91°. Heat index up to 98°. UV index up to 7. Wind south-southwest around 7 mph, gusting to 22 mph, in the morning, becoming 11 mph, gusting to 24 mph, in the afternoon. |
| Saturday night |
Fair to partly cloudy in the evening, becoming fair after midnight. Warm. Low 73°. Wind south-southwest around 10 mph, gusting to 20 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.