| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 04-May-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair to partly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog. Rain likely. Thunderstorms very likely, some severe. Low 57°. Wind west-southwest around 8 mph, gusting to 25 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Tuesday |
Dense overcast. Patchy light fog in the morning. A chance of rain. Thunderstorms very likely, some possibly severe. High 64°. UV index up to 5. Wind north around 8 mph, gusting to 26 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Tuesday night |
Cloudy. A chance of rain in the evening, then a slight chance of rain after midnight. Cool. Low 48°. Wind north around 7 mph, gusting to 24 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Wednesday |
Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Cool. High 60°. UV index up to 5. Wind north around 6 mph, gusting to 25 mph. |
| Wednesday night |
Partly to mostly cloudy in the evening, becoming fair to partly cloudy after midnight. Unusually cold. Low 39°. Wind north around 5 mph, gusting to 23 mph. |
| Thursday |
Partly cloudy. A slight chance of rain. Cool. High 61°. UV index up to 6. Wind west around 5 mph, gusting to 25 mph, in the morning, becoming 8 mph, gusting to 26 mph, in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Fair to partly cloudy. Unusually cold. Low 42°. Wind south-southwest around 7 mph, gusting to 19 mph. |
| Friday |
Partly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. High 70°. UV index up to 5. Wind south-southwest around 9 mph, gusting to 28 mph. |
| Friday night |
Partly cloudy in the evening, becoming clear after midnight. Moderate fog after midnight. Cool. Low 46°. Wind west-southwest around 5 mph, gusting to 16 mph. |
| Saturday |
Sunny in the morning, becoming mostly sunny in the afternoon. Moderate fog in the morning. High 77°. UV index up to 7. Wind west-southwest around 5 mph, gusting to 23 mph. |
| Saturday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog after midnight. A chance of rain in the evening, then rain likely after midnight. Scattered thundershowers possible. Low 54°. Wind south around 5 mph, gusting to 19 mph. Chance of precipitation 70 percent. Precipitation mostly between half an inch and one inch. |
| Sunday |
Mostly cloudy to cloudy. Patchy light fog in the morning. Rain likely. Scattered thunderstorms likely. High 68°. UV index up to 6. Wind west-southwest around 11 mph, gusting to 23 mph, in the morning, becoming west-northwest in the afternoon. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch. |
| Sunday night |
Cloudy in the evening, becoming partly to mostly cloudy after midnight. A slight chance of rain. Scattered thundershowers possible. Cool. Low 49°. Wind north-northwest around 12 mph, gusting to 23 mph, in the evening, becoming 6 mph, gusting to 19 mph, after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.