O'Fallon, MO Weather Forecast
Local 7-day forecast
Mostly Sunny
Track current conditions, temperature changes, wind, and the full daily outlook for O'Fallon, MO in one place.
Mostly sunny, with a high near 82. Northwest wind around 5 mph.
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: Aug 23, 2026 6:46 PM CDT.
The active forecast window currently covers Aug 23 to Aug 29, 2026 for O'Fallon, MO.
Page Snapshot
- Page focus
- city weather
- Forecast window
- Aug 23 to Aug 29, 2026
- Latest sync
- Aug 23, 2026 6:46 PM CDT
- Forecast office
- LSX
- Source
- NOAA / NWS
Daily Outlook
This Week in O'Fallon
Wednesday looks like the warmest upcoming period in O'Fallon at 88 degrees F.
Tonight is the coolest period ahead with temperatures near 55 degrees F.
The strongest winds are forecast for Saturday Night at about 7 mph S.
Precipitation is mentioned in 2 upcoming forecast periods.
Forecast Details
- Last updated
- Aug 23, 2026 6:46 PM CDT
- Coverage
- 7 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
Patchy fog after 5am. Partly cloudy, with a low around 55. North wind 0 to 3 mph.
Patchy fog before 9am. Mostly sunny, with a high near 82. Southeast wind 0 to 3 mph.
Mostly clear, with a low around 60. East wind around 3 mph.
Mostly sunny, with a high near 85. Southeast wind around 5 mph.
Partly cloudy, with a low around 68.
Partly sunny, with a high near 88.
Mostly clear, with a low around 66.
Sunny, with a high near 86.
Mostly clear, with a low around 64.
Sunny, with a high near 85.
Partly cloudy, with a low around 66.
A slight chance of rain showers between 7am and 1pm. Partly sunny, with a high near 87. Chance of precipitation is 20%.
A slight chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 71. Chance of precipitation is 20%.
Detailed Forecast
| Period | Conditions | Temp | Wind |
|---|---|---|---|
|
This Afternoon
Aug 23
|
Mostly Sunny
|
82°F |
5 mph
NW
|
|
Tonight
Aug 23
|
Partly Cloudy then Patchy Fog
|
55°F |
0 to 3 mph
N
|
|
Monday
Aug 24
|
Patchy Fog then Mostly Sunny
|
82°F |
0 to 3 mph
SE
|
|
Monday Night
Aug 24
|
Mostly Clear
|
60°F |
3 mph
E
|
|
Tuesday
Aug 25
|
Mostly Sunny
|
85°F |
5 mph
SE
|
|
Tuesday Night
Aug 25
|
Partly Cloudy
|
68°F |
2 mph
SE
|
|
Wednesday
Aug 26
|
Partly Sunny
|
88°F |
1 to 5 mph
SW
|
|
Wednesday Night
Aug 26
|
Mostly Clear
|
66°F |
3 mph
W
|
|
Thursday
Aug 27
|
Sunny
|
86°F |
2 to 6 mph
NW
|
|
Thursday Night
Aug 27
|
Mostly Clear
|
64°F |
0 to 3 mph
N
|
|
Friday
Aug 28
|
Sunny
|
85°F |
2 mph
NE
|
|
Friday Night
Aug 28
|
Partly Cloudy
|
66°F |
2 mph
E
|
|
Saturday
Aug 29
|
Slight Chance Rain Showers
|
87°F |
2 to 6 mph
S
|
|
Saturday Night
Aug 29
|
Partly Cloudy then Slight Chance Showers And Thunderstorms
|
71°F |
7 mph
S
|
Nearby Forecasts
Explore weather pages for nearby cities and major places around O'Fallon.
