| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Tuesday, 31-Mar-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Mostly cloudy to cloudy in the evening, becoming dense overcast after midnight. Patchy light fog after midnight. Rain likely. Thunderstorms very likely, some severe. Low 55°. Wind west around 4 mph, gusting to 16 mph, in the evening, becoming north after midnight. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Wednesday |
Dense overcast in the morning, becoming cloudy in the afternoon. Patchy light fog. Rain likely in the morning, then a chance of rain in the afternoon. High 59°. Wind northeast around 5 mph. Chance of precipitation 80 percent. Precipitation mostly around half an inch. |
| Wednesday night |
Mostly cloudy to cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog in the evening. A slight chance of rain. Low 56°, but temperatures rising after midnight. Wind east-southeast around 6 mph in the evening, becoming south-southeast around 10 mph, gusting to 16 mph, after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday |
Cloudy in the morning, becoming partly to mostly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thundershowers possible. Breezy and warm. High 75°. UV index up to 4. Wind south-southeast around 14 mph, gusting to 28 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Thursday night |
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Mild. Low 61°. Wind south-southwest around 10 mph, gusting to 24 mph, in the evening, becoming 6 mph, gusting to 16 mph, after midnight. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Friday |
Mostly cloudy in the morning, becoming cloudy in the afternoon. Moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Mild. High 72°. Wind south-southwest around 7 mph, gusting to 20 mph, in the morning, becoming 10 mph, gusting to 21 mph, in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Mostly cloudy to cloudy in the evening, becoming dense overcast after midnight. Light to moderate fog. Rain very likely. Scattered thundershowers possible. Mild. Low 64°. Wind south around 8 mph, gusting to 18 mph. Chance of precipitation 90 percent. Precipitation mostly between 1 and 2 inches. |
| Saturday |
Dense overcast in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning, then moderate fog in the afternoon. Rain very likely. Scattered thundershowers possible. High 66°, but temperatures falling in the afternoon. Wind west-northwest around 9 mph, gusting to 26 mph. Chance of precipitation 80 percent. Precipitation mostly around 3 inches. |
| Saturday night |
Fair in the evening, becoming clear after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Low 45°. Wind west-northwest around 9 mph, gusting to 27 mph. |
| Sunday |
Sunny. Moderate fog in the morning. High 52°. UV index up to 6. Wind west-northwest around 10 mph, gusting to 27 mph. |
| Sunday night |
Clear. Patchy light fog after midnight. Low 41°. Wind northwest around 5 mph, gusting to 22 mph. |
| Monday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. High 61°. UV index up to 8. Wind south-southeast around 7 mph, gusting to 25 mph. |
| Monday night |
Partly cloudy. Low 45°. Wind south-southeast around 8 mph, gusting to 19 mph, in the evening, becoming west-southwest after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.