| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Saturday, 30-May-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Mostly cloudy in the evening, becoming cloudy after midnight. A slight chance of rain. Scattered thunderstorms likely. Low 66°. Wind east around 6 mph, gusting to 17 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. A slight chance of rain. Scattered thunderstorms likely. High 85°. UV index up to 8. Wind east-southeast around 6 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Scattered thunderstorms likely. Low 63°. Wind east-southeast around 4 mph, gusting to 19 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Thunderstorms very likely, some possibly severe. High 84°. UV index up to 6. Wind southeast around 3 mph, gusting to 23 mph, in the morning, becoming northeast in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Monday night |
Fair in the evening, becoming partly cloudy after midnight. Light to moderate fog after midnight. Low 63°. Wind north-northeast around 4 mph, gusting to 18 mph. |
| Tuesday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. High 82°. UV index up to 7. Wind east-northeast around 8 mph, gusting to 26 mph. |
| Tuesday night |
Mostly clear in the evening, becoming fair after midnight. Relatively cool. Low 58°. Wind east around 7 mph, gusting to 23 mph, in the evening, becoming 4 mph after midnight. |
| Wednesday |
Sunny. High 83°. UV index up to 9. Wind east around 5 mph, gusting to 25 mph. |
| Wednesday night |
Fair in the evening, becoming partly cloudy after midnight. Relatively cool. Low 58°. Wind east around 4 mph, gusting to 21 mph, in the evening, becoming southeast after midnight. |
| Thursday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Hot. High 86°. UV index up to 8. Wind south around 6 mph, gusting to 25 mph. |
| Thursday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Low 60°. Wind south around 5 mph, gusting to 20 mph. |
| Friday |
Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Hot. High 89°. UV index up to 8. Wind southwest around 7 mph, gusting to 26 mph. |
| Friday night |
Fair in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 62°. Wind south-southeast around 5 mph, gusting to 17 mph, in the evening, becoming south-southwest after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.