| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Thursday, 03-Sep-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Sunny. Near record heat. High 101°. Heat index up to 109°. UV index up to 8. Wind southwest around 6 mph, gusting to 25 mph. |
| Tonight |
Mostly clear in the evening, becoming clear after midnight. Warm. Low 75°. Wind south around 4 mph, gusting to 19 mph. |
| Friday |
Sunny. Extremely hot. High 100°. Heat index up to 108°. UV index up to 7. Wind southwest around 5 mph, gusting to 24 mph. |
| Friday night |
Fair to partly cloudy. Warm. Low 75°. Wind south-southwest around 3 mph. |
| Saturday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Extremely hot. High 99°. Heat index up to 107°. UV index up to 7. Wind west-southwest around 4 mph, gusting to 22 mph, in the morning, becoming northwest in the afternoon. |
| Saturday night |
Partly cloudy in the evening, becoming clear after midnight. Low 70°. Wind north-northeast around 4 mph. |
| Sunday |
Sunny. Hot. High 91°. Heat index up to 96°. UV index up to 7. Wind north-northeast around 7 mph, gusting to 25 mph. |
| Sunday night |
Fair to partly cloudy in the evening, becoming fair after midnight. Low 65°. Wind northeast around 6 mph, gusting to 20 mph, in the evening, becoming east after midnight. |
| Monday |
Sunny. Hot. High 90°. UV index up to 8. Wind east around 5 mph, gusting to 24 mph. |
| Monday night |
Fair to partly cloudy in the evening, becoming clear after midnight. Low 64°. Wind east around 5 mph, gusting to 18 mph. |
| Tuesday |
Sunny. Very hot. High 94°. UV index up to 8. Wind southeast around 4 mph, gusting to 21 mph. |
| Tuesday night |
Mostly clear in the evening, becoming clear after midnight. Low 67°. Wind south-southeast around 7 mph. |
| Wednesday |
Sunny. Near record heat. High 102°. Heat index up to 107°. UV index up to 7. Wind west-southwest around 9 mph, gusting to 24 mph. |
| Wednesday night |
Partly cloudy in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 69°. Wind south-southwest around 8 mph, gusting to 19 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.