| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 26-Aug-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 67°. Wind north-northwest around 4 mph, gusting to 23 mph. |
| Thursday |
Sunny. Patchy light fog in the morning. Hot. High 86°. UV index up to 7. Wind northwest around 5 mph, gusting to 23 mph. |
| Thursday night |
Clear. Patchy light fog after midnight. Low 63°. Wind north-northeast around 3 mph, gusting to 18 mph. |
| Friday |
Sunny. Patchy light fog in the morning. Hot. High 86°. UV index up to 7. Wind north-northeast around 3 mph, gusting to 21 mph. |
| Friday night |
Fair in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 61°. Wind east around 3 mph, gusting to 16 mph. |
| Saturday |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 89°. UV index up to 7. Wind south-southeast around 5 mph, gusting to 22 mph. |
| Saturday night |
Fair to partly cloudy. Patchy light fog after midnight. Low 66°. Wind south around 6 mph, gusting to 17 mph. |
| Sunday |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 94°. Heat index up to 98°. UV index up to 8. Wind south around 8 mph, gusting to 24 mph. |
| Sunday night |
Fair to partly cloudy in the evening, becoming fair after midnight. Low 69°. Wind south-southeast around 7 mph, gusting to 17 mph. |
| Monday |
Partly to mostly sunny in the morning, becoming sunny in the afternoon. Very hot. High 97°. Heat index up to 103°. UV index up to 8. Wind south-southwest around 8 mph, gusting to 24 mph. |
| Monday night |
Clear. Low 70°. Wind south-southwest around 7 mph, gusting to 16 mph. |
| Tuesday |
Sunny. Very hot. High 99°. Heat index up to 106°. UV index up to 7. Wind south-southwest around 8 mph, gusting to 23 mph. |
| Tuesday night |
Mostly clear in the evening, becoming clear after midnight. Low 71°. Wind south-southwest around 6 mph, gusting to 16 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.