| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Saturday, 25-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Warm. Low 83°. Wind south-southeast around 2 mph, gusting to 20 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. A chance of rain. Very hot. High 99°. Heat index up to 118°. UV index up to 9. Wind southwest around 5 mph, gusting to 25 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Warm. Low 81°. Wind west-southwest around 4 mph, gusting to 19 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Light to moderate fog in the morning. A slight chance of rain. Precipitation showery or intermittent. Very hot. High 97°. Heat index up to 114°. UV index up to 9. Wind west-southwest around 8 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Monday night |
Mostly clear in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 77°. Wind west around 6 mph, gusting to 19 mph. |
| Tuesday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 97°. Heat index up to 107°. UV index up to 9. Wind northwest around 6 mph, gusting to 25 mph. |
| Tuesday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. A slight chance of rain. Low 73°. Wind northeast around 4 mph, gusting to 20 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday |
Partly cloudy in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. High 89°. Heat index up to 95°. UV index up to 9. Wind east-northeast around 5 mph, gusting to 24 mph. |
| Wednesday night |
Clear in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 69°. Wind east-northeast around 3 mph, gusting to 22 mph. |
| Thursday |
Partly cloudy. Patchy light fog in the morning. High 88°. Heat index up to 92°. UV index up to 7. Wind east-southeast around 2 mph, gusting to 23 mph, in the morning, becoming northeast around 5 mph, gusting to 23 mph, in the afternoon. |
| Thursday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 68°. Wind east around 3 mph, gusting to 20 mph. |
| Friday |
Cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. High 83°. UV index up to 6. Wind east-southeast around 5 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Mostly cloudy in the evening, becoming partly to mostly cloudy after midnight. Relatively cool. Low 67°. Wind east around 4 mph, gusting to 20 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.
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