| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Thursday, 12-Mar-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Breezy. Low 40°. Wind chill ranging from 31 to 47. Wind south-southwest around 11 mph, gusting to 26 mph, in the evening, becoming 16 mph, gusting to 24 mph, after midnight. |
| Friday |
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Breezy. High 59°. Wind west-northwest around 14 mph, gusting to 29 mph, in the morning, becoming 11 mph, gusting to 29 mph, in the afternoon. |
| Friday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Low 36°. Wind northwest around 4 mph, gusting to 21 mph, in the evening, becoming east-northeast after midnight. |
| Saturday |
Partly cloudy. Mild. High 64°. UV index up to 5. Wind east-southeast around 9 mph, gusting to 27 mph. |
| Saturday night |
Mostly cloudy. Low 47°. Wind south-southeast around 9 mph, gusting to 21 mph. |
| Sunday |
Mostly cloudy to cloudy in the morning, becoming dense overcast in the afternoon. A slight chance of rain in the morning, then rain likely in the afternoon. Scattered thundershowers possible. Breezy and mild. High 65°. Wind south-southeast around 13 mph, gusting to 27 mph, in the morning, becoming west-southwest around 16 mph, gusting to 29 mph, in the afternoon. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch. |
| Sunday night |
Dense overcast. A mix of rain and snow likely in the evening, then a chance of a mix of rain and snow after midnight. Windy and cold. Low 27°. Wind chill ranging from 18 to 43. Wind west-northwest around 17 mph, gusting to 36 mph. Chance of precipitation 80 percent. Precipitation (liquid equivalent) mostly between a quarter and half an inch. Little or no snow accumulation expected. |
| Monday |
Cloudy in the morning, becoming mostly cloudy in the afternoon. Windy and very cold. High 29°, but temperatures falling in the afternoon. Wind chill ranging from 13 to 18. Wind northwest around 16 mph, gusting to 34 mph. |
| Monday night |
Mostly clear in the evening, becoming clear after midnight. Very cold. Low 20°. Wind chill as low as 11. Wind northwest around 9 mph, gusting to 27 mph. |
| Tuesday |
Partly to mostly sunny in the morning, becoming mostly cloudy to cloudy in the afternoon. High 42°. Wind west around 4 mph, gusting to 26 mph, in the morning, becoming south in the afternoon. |
| Tuesday night |
Cloudy in the evening, becoming mostly cloudy after midnight. Low 33°. Wind chill ranging from 27 to 37. Wind southeast around 8 mph, gusting to 22 mph. |
| Wednesday |
Partly cloudy. Breezy and mild. High 63°. UV index up to 5. Wind south-southwest around 12 mph, gusting to 29 mph. |
| Wednesday night |
Fair in the evening, becoming cloudy after midnight. Low 41°. Wind west around 4 mph, gusting to 22 mph, in the evening, becoming north after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.