| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 08-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 in the evening, then moderate fog after midnight. Low 74°. Wind south around 4 mph, gusting to 16 mph. |
| Thursday |
Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog. A slight chance of rain in the morning, then rain likely in the afternoon. Scattered thundershowers possible. High 89°. Heat index up to 97°. UV index up to 8. Wind west-southwest around 3 mph, gusting to 18 mph. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch. |
| Thursday night |
Moderate fog. Rain very likely. Thunderstorms very likely, some possibly severe. Low 77°. Wind west around 4 mph. Chance of precipitation 80 percent. Precipitation mostly around half an inch. |
| Friday |
Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Moderate fog in the morning, then light to moderate fog in the afternoon. Rain likely. Thunderstorms very likely, some possibly severe. High 85°. Heat index up to 93°. UV index up to 6. Wind south-southwest around 6 mph, gusting to 18 mph, in the morning, becoming west-northwest in the afternoon. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch. |
| Friday night |
Partly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Low 74°. Wind northeast around 3 mph, gusting to 16 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Saturday |
Partly cloudy in the morning, becoming sunny in the afternoon. Moderate fog in the morning. A slight chance of rain. High 88°. Heat index up to 95°. UV index up to 8. Wind north-northeast around 6 mph, gusting to 24 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday night |
Clear. Light to moderate fog after midnight. Low 69°. Wind north-northeast around 4 mph, gusting to 23 mph. |
| Sunday |
Sunny. Light to moderate fog in the morning. High 88°. Heat index up to 93°. UV index up to 9. Wind northeast around 4 mph, gusting to 22 mph, in the morning, becoming 7 mph, gusting to 24 mph, in the afternoon. |
| Sunday night |
Clear. Patchy light fog after midnight. Low 68°. Wind east-northeast around 4 mph, gusting to 21 mph. |
| Monday |
Sunny. Patchy light fog in the morning. High 89°. Heat index up to 94°. UV index up to 9. Wind east-northeast around 5 mph, gusting to 23 mph. |
| Monday night |
Clear. Patchy light fog after midnight. Low 68°. Wind east-northeast around 5 mph, gusting to 21 mph, in the evening, becoming 2 mph after midnight. |
| Tuesday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. High 88°. Heat index up to 93°. UV index up to 8. Wind east around 4 mph, gusting to 23 mph. |
| Tuesday night |
Mostly clear in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 70°. Wind east around 2 mph, gusting to 18 mph, in the evening, becoming south after midnight. |
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