Weather in O Fallon, MO
Updated 2026-09-26 07:45 local time · ZIP codes 63366, 63368
Overcast
No government weather alerts were returned for this location at the latest update.
Next hours
62°13% rain62°13% rain62°13% rain63°12% rain65°11% rain
64°12% rain63°14% rain63°15% rain63°13% rain63°14% rain62°15% rain
61°26% rain3-day weather forecast
Weather details
Sunrise, sunset and moon
Key weather changes ahead
Weather insights for today
Rain chance stays relatively low over the next 12 hours (up to 26%).
It feels like 59°F with winds near 4 mph.
65°F, 11% rain chance and 3 mph wind.
Visibility is around 6 mi; gusts may reach 13 mph.
Current temperature is 62°F, wind 4 mph, rain chance up to 26%.
UV index is 0.
Local weather characteristics in O Fallon
Missouri sits where different air masses often meet, producing hot humid summers, cold winter spells, rapid weather changes and frequent thunderstorms.
O Fallon is part of the Midwest weather region. The forecast point is near 38.79°N latitude and 90.78°W longitude. Local temperature, wind and precipitation can still differ from nearby places, especially where terrain, coastlines or urban development create small-scale weather changes.
O Fallon weather today
Overcast and 62°F in O Fallon, MO. Today's high is 65°F with a 41% rain chance. Winds are around 4 mph with gusts near 8 mph. Relative humidity is 55%, pressure is 30.12 inHg, and visibility is about 6 miles.
Tonight and tomorrow in O Fallon
Sunrise is at 06:54 AM and sunset is at 06:54 PM. Tomorrow's forecast calls for Sunny with a high near 76°F and a low near 59°F. The maximum rain chance is 36%.