| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Saturday, 29-Aug-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Partly cloudy in the evening, becoming clear after midnight. Low 65°. Wind south-southwest around 6 mph, gusting to 22 mph. |
| Sunday |
Partly to mostly sunny. Very hot. High 94°. UV index up to 8. Wind south-southwest around 7 mph, gusting to 23 mph. |
| Sunday night |
Clear in the evening, becoming fair after midnight. Low 69°. Wind south-southeast around 6 mph, gusting to 17 mph. |
| Monday |
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Very hot. High 98°. UV index up to 8. Wind south-southwest around 7 mph, gusting to 23 mph. |
| Monday night |
Fair to partly cloudy in the evening, becoming clear after midnight. Low 70°. Wind south-southwest around 5 mph, gusting to 16 mph. |
| Tuesday |
Sunny. Extremely hot. High 100°. Heat index up to 105°. UV index up to 8. Wind south-southwest around 5 mph, gusting to 22 mph. |
| Tuesday night |
Clear. Low 71°. Wind south around 4 mph. |
| Wednesday |
Sunny. Extremely hot. High 100°. Heat index up to 107°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 23 mph. |
| Wednesday night |
Clear. Low 72°. Wind south-southwest around 3 mph. |
| Thursday |
Sunny. Extremely hot. High 101°. Heat index up to 109°. UV index up to 8. Wind southwest around 5 mph, gusting to 21 mph. |
| Thursday night |
Mostly clear in the evening, becoming fair after midnight. Low 73°. Wind southeast around 2 mph in the evening, becoming south after midnight. |
| Friday |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Extremely hot. High 100°. Heat index up to 109°. UV index up to 7. Wind southwest around 5 mph, gusting to 21 mph. |
| Friday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Warm. Low 74°. Wind southeast around 4 mph in the evening, becoming southwest after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.