| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Tuesday, 31-Mar-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Mostly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. Unusually hot. High 86°. UV index up to 5. Wind south-southwest around 11 mph, gusting to 30 mph. |
| Tonight |
Mostly cloudy in the evening, becoming cloudy after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Thunderstorms very likely, some possibly severe. Mild. Low 64°. Wind southwest around 2 mph, gusting to 21 mph, in the evening, becoming north-northwest after midnight. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday |
Dense overcast in the morning, becoming mostly cloudy in the afternoon. Rain likely. Scattered thunderstorms likely. Warm. High 75°. UV index up to 4. Wind east-northeast around 2 mph, gusting to 18 mph, in the morning, becoming southeast in the afternoon. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Wednesday night |
Partly cloudy in the evening, becoming mostly cloudy after midnight. Mild. Low 65°. Wind southeast around 7 mph, gusting to 17 mph, in the evening, becoming 12 mph, gusting to 20 mph, after midnight. |
| Thursday |
Cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Thunderstorms very likely, some severe. Breezy and unusually warm. High 78°. Wind south around 15 mph, gusting to 33 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Fair in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A slight chance of rain. Scattered thunderstorms likely. Mild. Low 61°. Wind south around 10 mph, gusting to 28 mph, in the evening, becoming 6 mph, gusting to 17 mph, after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Friday |
Partly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. Light to moderate 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. Warm. High 74°. Wind south around 9 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Mostly cloudy to cloudy in the evening, becoming dense overcast after midnight. Moderate fog in the evening, then light to moderate fog after midnight. Rain very likely. Thunderstorms very likely, some severe. Mild. Low 63°. Wind south around 7 mph, gusting to 20 mph. Chance of precipitation 80 percent. Precipitation mostly around an inch. |
| Saturday |
Dense overcast in the morning, becoming cloudy in the afternoon. Light to moderate fog in the morning, then patchy light fog in the afternoon. Rain likely in the morning, then a chance of rain in the afternoon. Thunderstorms very likely, some severe. High 64°, but temperatures falling in the afternoon. Wind northwest around 9 mph, gusting to 28 mph. Chance of precipitation 80 percent. Precipitation mostly around half an inch. |
| Saturday night |
Mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog. Low 42°. Wind northwest around 10 mph, gusting to 26 mph. |
| Sunday |
Sunny. Patchy light fog in the morning. High 53°. UV index up to 6. Wind northwest around 11 mph, gusting to 28 mph. |
| Sunday night |
Clear. Low 38°. Wind north-northwest around 5 mph, gusting to 25 mph, in the evening, becoming northeast after midnight. |
| Monday |
Sunny. High 62°. UV index up to 8. Wind east around 4 mph, gusting to 23 mph. |
| Monday night |
Clear. Low 42°. Wind southeast around 5 mph, gusting to 19 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.