O'Fallon, MO Weather Forecast
Local 7-day forecast
Mostly Sunny then Scattered Showers And Thunderstorms
Track current conditions, temperature changes, wind, and the full daily outlook for O'Fallon, MO in one place.
Scattered showers and thunderstorms after noon. Mostly sunny, with a high near 92. Heat index values as high as 101. Southwest wind around 5 mph. Chance of precipitation is 50%.
Local Weather Overview
This forecast page for O'Fallon, MO is designed for quick trip planning, giving you a clean read on daytime highs, overnight lows, and changing conditions across the upcoming forecast window. Latest sync: Jul 8, 2026 1:50 PM CDT.
The active forecast window currently covers Jul 9 to Jul 14, 2026 for O'Fallon, MO.
Page Snapshot
- Page focus
- city weather
- Forecast window
- Jul 9 to Jul 14, 2026
- Latest sync
- Jul 8, 2026 1:50 PM CDT
- Forecast office
- LSX
- Source
- NOAA / NWS
Daily Outlook
This Week in O'Fallon
Thursday looks like the warmest upcoming period in O'Fallon at 92 degrees F.
Saturday Night is the coolest period ahead with temperatures near 70 degrees F.
The strongest winds are forecast for Sunday at about 2 to 6 mph NE.
Precipitation is mentioned in 8 upcoming forecast periods.
Forecast Details
- Last updated
- Jul 8, 2026 1:50 PM CDT
- Coverage
- 6 days
- Time zone
- America/Chicago
- Forecast office
- LSX
- Radar station
- KLSX
Weather data is provided by the National Weather Service and refreshed automatically for U.S. locations.
Open NOAA sourceExtended Forecast
Scattered showers and thunderstorms before 1am, then scattered showers and thunderstorms between 1am and 4am, then isolated showers and thunderstorms. Mostly cloudy, with a low around 73. Heat index values as high as 100. Southwest wind around 5 mph. Chance of precipitation is 50%.
Showers and thunderstorms likely. Partly sunny, with a high near 89. West wind around 5 mph. Chance of precipitation is 60%.
Showers and thunderstorms likely. Mostly cloudy, with a low around 71. Chance of precipitation is 70%.
Showers and thunderstorms likely. Partly sunny, with a high near 87. Chance of precipitation is 70%.
A chance of showers and thunderstorms. Partly cloudy, with a low around 70. Chance of precipitation is 40%.
A chance of showers and thunderstorms. Mostly sunny, with a high near 88. Chance of precipitation is 30%.
A slight chance of showers and thunderstorms before 7pm. Mostly clear, with a low around 70. Chance of precipitation is 20%.
Sunny, with a high near 90.
Clear, with a low around 71.
Sunny, with a high near 92.
Mostly clear, with a low around 72.
Detailed Forecast
| Period | Conditions | Temp | Wind |
|---|---|---|---|
|
Thursday
Jul 9
|
Mostly Sunny then Scattered Showers And Thunderstorms
|
92°F |
5 mph
SW
|
|
Thursday Night
Jul 9
|
Scattered Showers And Thunderstorms
|
73°F |
5 mph
SW
|
|
Friday
Jul 10
|
Showers And Thunderstorms Likely
|
89°F |
5 mph
W
|
|
Friday Night
Jul 10
|
Showers And Thunderstorms Likely
|
71°F |
1 to 5 mph
SW
|
|
Saturday
Jul 11
|
Showers And Thunderstorms Likely
|
87°F |
5 mph
W
|
|
Saturday Night
Jul 11
|
Chance Showers And Thunderstorms
|
70°F |
3 mph
N
|
|
Sunday
Jul 12
|
Chance Showers And Thunderstorms
|
88°F |
2 to 6 mph
NE
|
|
Sunday Night
Jul 12
|
Slight Chance Showers And Thunderstorms then Mostly Clear
|
70°F |
1 to 6 mph
NE
|
|
Monday
Jul 13
|
Sunny
|
90°F |
5 mph
NE
|
|
Monday Night
Jul 13
|
Clear
|
71°F |
1 to 5 mph
E
|
|
Tuesday
Jul 14
|
Sunny
|
92°F |
3 mph
N
|
|
Tuesday Night
Jul 14
|
Mostly Clear
|
72°F |
2 mph
SE
|
Nearby Forecasts
Explore weather pages for nearby cities and major places around O'Fallon.
