| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Thursday, 02-Jul-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 97°. Heat index up to 105°. UV index up to 10. Wind south around 4 mph, gusting to 24 mph. |
| Tonight |
Partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 74°. Wind south around 5 mph, gusting to 20 mph. |
| Friday |
Mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thunderstorms likely, some possibly severe. Hot. High 96°. Heat index up to 107°. UV index up to 9. Wind south around 5 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog. Low 75°. Wind southeast around 4 mph, gusting to 17 mph, in the evening, becoming south-southwest after midnight. |
| Saturday |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Thunderstorms very likely, some severe. Hot. High 96°. Heat index up to 108°. UV index up to 8. Wind south around 4 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Saturday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Thunderstorms very likely, some possibly severe. Low 75°. Wind southwest around 4 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Sunday |
Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Moderate fog in the morning. A slight chance of rain. Scattered thunderstorms likely, some possibly severe. Hot. High 92°. Heat index up to 101°. UV index up to 10. Wind west-northwest around 5 mph, gusting to 22 mph, in the morning, becoming north-northwest in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A slight chance of rain. Scattered thunderstorms likely, some possibly severe. Low 73°. Wind north-northeast around 2 mph, gusting to 20 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Partly cloudy. Moderate fog in the morning. A chance of rain. Scattered thunderstorms likely. Hot. High 90°. Heat index up to 98°. UV index up to 9. Wind north-northeast around 3 mph, gusting to 22 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Monday night |
Partly cloudy. Patchy light fog in the evening, then moderate fog after midnight. A slight chance of rain. Scattered thundershowers possible. Low 73°. Wind north-northeast around 4 mph, gusting to 18 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. A slight chance of rain. Scattered thundershowers possible. High 90°. Heat index up to 97°. UV index up to 8. Wind east-northeast around 4 mph, gusting to 21 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 71°. Wind east-northeast around 3 mph, gusting to 17 mph. |
| Wednesday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. Hot. High 90°. Heat index up to 97°. UV index up to 10. Wind east-northeast around 2 mph, gusting to 21 mph. |
| Wednesday night |
Mostly cloudy in the evening, becoming fair to partly cloudy after midnight. Moderate fog after midnight. Low 71°. Wind east around 5 mph, gusting to 18 mph, in the evening, becoming southeast after midnight. |
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