Missouri · NWS LSX office

O'Fallon, MO weather

It is 46°F and clear at St. Louis, Spirit Of St. Louis Airport as of Oct 28, 4:05 AM CDT. Overnight: Partly Cloudy, low near 52°F. Forecast from the National Weather Service, issued Oct 28, 1:26 AM CDT.

Updated Oct 28, 4:17 AM CDT (snapshot)

Current conditions

Temperature

46°F

Clear

Wind

Calm

Humidity 100% · dew point 46°F

Pressure · visibility

30.20 inHg

Visibility 7 mi

Observed at St. Louis, Spirit Of St. Louis Airport (KSUS), Oct 28, 4:05 AM CDT. Station readings can lag or be missing.

Alerts for this area

No active NWS alerts cover the O'Fallon forecast zone right now.

Around the NWS LSX forecast area

No active alerts in zones served by the LSX office near O'Fallon.

From the alert snapshot of Oct 28, 2026, 5:12 AM EDT. No alerts are active anywhere in Missouri.

For official warnings, check weather.gov and your local authorities. OpenForecast repeats National Weather Service alerts and may be delayed or incomplete. Follow instructions from emergency officials.

Next 24 hours

Hourly forecast for O'Fallon (local time)
TimeTempForecastPrecip. chanceWind
Wed 6 AM52°FMostly Sunny1%S 3 mph
Wed 7 AM52°FMostly Sunny1%S 3 mph
Wed 8 AM53°FMostly Sunny1%S 3 mph
Wed 9 AM58°FSunny0%S 5 mph
Wed 10 AM64°FSunny0%S 5 mph
Wed 11 AM69°FSunny0%S 6 mph
Wed 12 PM73°FSunny1%S 6 mph
Wed 1 PM76°FSunny0%S 7 mph
Wed 2 PM78°FSunny0%S 8 mph
Wed 3 PM79°FSunny0%S 8 mph
Wed 4 PM79°FSunny0%S 8 mph
Wed 5 PM77°FSunny0%S 7 mph
Wed 6 PM73°FMostly Clear0%S 6 mph
Wed 7 PM68°FClear1%S 6 mph
Wed 8 PM65°FClear1%S 6 mph
Wed 9 PM64°FClear1%S 6 mph
Wed 10 PM63°FMostly Clear1%S 6 mph
Wed 11 PM61°FMostly Clear1%S 6 mph
Thu 12 AM61°FMostly Clear1%S 6 mph
Thu 1 AM60°FMostly Clear1%S 5 mph
Thu 2 AM59°FMostly Clear1%S 5 mph
Thu 3 AM58°FMostly Clear1%S 5 mph
Thu 4 AM57°FMostly Clear1%S 5 mph
Thu 5 AM57°FClear1%S 5 mph

Hourly values come from the NWS gridded forecast for the 2.5 km grid square that covers the city's center point. Conditions elsewhere in O'Fallon can differ.

7-day forecast

Overnight

Low 52°F

Partly cloudy, with a low around 52. South wind around 3 mph.

Wednesday

High 79°F·Low 55°F

Sunny, with a high near 79. South wind 3 to 8 mph.

Wednesday Night: Mostly clear, with a low around 55. South wind around 6 mph.

Thursday

High 81°F·Low 57°F

Sunny, with a high near 81. Southwest wind 2 to 6 mph.

Thursday Night: Partly cloudy, with a low around 57. Northeast wind around 2 mph.

Friday

High 78°F·Low 56°F

Partly sunny, with a high near 78.

Friday Night: Mostly cloudy, with a low around 56.

Saturday

High 72°F·Low 54°F

A chance of rain showers after 1pm. Cloudy, with a high near 72. Chance of precipitation is 30%.

Saturday Night: A chance of rain showers. Mostly cloudy, with a low around 54. Chance of precipitation is 50%.

Sunday

High 71°F·Low 54°F

A chance of rain showers before noon. Mostly cloudy, with a high near 71. Chance of precipitation is 30%.

Sunday Night: A slight chance of rain showers after midnight. Mostly cloudy, with a low around 54. Chance of precipitation is 20%.

Monday

High 71°F·Low 55°F

A chance of rain showers. Mostly cloudy, with a high near 71. Chance of precipitation is 50%.

Monday Night: Showers and thunderstorms likely. Mostly cloudy, with a low around 55. Chance of precipitation is 60%.

Tuesday

High 70°F

Rain showers likely. Mostly cloudy, with a high near 70. Chance of precipitation is 60%.

Nearby cities

Larger cities in the area

Other cities in St. Charles County

See every city we cover in Missouri, or check all active alerts.

About this forecast

Forecast office
O'Fallon is served by the National Weather Service LSX forecast office, forecast zone MOZ061, county zone MOC183.
Location used
The Census Bureau's internal point for O'Fallon (38.7847, -90.7207), in St. Charles County. Population: 95,355 (2024 estimate), number 7 of the 36 Missouri cities on this site.
Radar
Nearest NWS radar: KLSX. View it on radar.weather.gov.

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Sources

  • Forecast, hourly forecast, observations and alerts: National Weather Service API, api.weather.gov/points/38.7847,-90.7207 (forecast issued Oct 28, 1:26 AM CDT).
  • Official forecast page: forecast.weather.gov.
  • City location and population: U.S. Census Bureau, Vintage 2024 population estimates and 2024 Gazetteer files.
  • Snapshot taken Oct 28, 2026. The NWS and Census Bureau do not endorse OpenForecast.

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