| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Friday, 28-Aug-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Sunny. High 85°. UV index up to 7. Wind north-northeast around 3 mph, gusting to 21 mph. |
| Tonight |
Mostly clear in the evening, becoming fair after midnight. Relatively cool. Low 59°. Wind east-southeast around 2 mph. |
| Saturday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Hot. High 88°. UV index up to 7. Wind south-southeast around 5 mph, gusting to 23 mph. |
| Saturday night |
Partly cloudy in the evening, becoming fair after midnight. Low 63°. Wind south-southeast around 5 mph, gusting to 17 mph. |
| Sunday |
Mostly sunny in the morning, becoming sunny in the afternoon. Very hot. High 93°. UV index up to 8. Wind south-southeast around 7 mph, gusting to 24 mph. |
| Sunday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Low 67°. Wind south-southeast around 6 mph, gusting to 16 mph. |
| Monday |
Partly to mostly sunny. Very hot. High 95°. Heat index up to 99°. UV index up to 7. Wind south-southeast around 6 mph, gusting to 20 mph, in the morning, becoming south-southwest in the afternoon. |
| Monday night |
Fair to partly cloudy in the evening, becoming clear after midnight. Low 69°. Wind south around 6 mph. |
| Tuesday |
Sunny. Patchy light fog in the morning. Very hot. High 96°. Heat index up to 102°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 19 mph. |
| Tuesday night |
Clear. Patchy light fog after midnight. Low 70°. Wind south around 7 mph. |
| Wednesday |
Sunny. Patchy light fog in the morning. Very hot. High 96°. Heat index up to 103°. UV index up to 8. Wind southwest around 6 mph, gusting to 20 mph. |
| Wednesday night |
Clear in the evening, becoming fair to partly cloudy after midnight. Low 72°. Wind southwest around 6 mph. |
| Thursday |
Mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Very hot. High 98°. Heat index up to 108°. UV index up to 7. Wind southwest around 6 mph, gusting to 19 mph. |
| Thursday night |
Mostly clear in the evening, becoming clear after midnight. Low 72°. Wind south-southwest around 5 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.