10-Day Weather Forecast - O'Fallon, MO

Mostly cloudy in the morning, then partly sunny with a slight chance of showers and thunderstorms in the afternoon. Humid with highs in the mid 90s. West winds 5 to 10 mph. Gusts up to 20 mph in the morning. Chance of rain 20 percent. Heat index values up to 109.

Partly cloudy with a chance of showers and thunderstorms in the evening, then mostly cloudy with a slight chance of showers and thunderstorms after midnight. Humid with lows in the lower 70s. North winds 5 to 10 mph. Chance of rain 40 percent. Heat index values up to 107 early in the evening.

Mostly sunny. Highs in the mid 80s. North winds 5 to 10 mph.

Partly cloudy in the evening, then becoming mostly clear. Lows in the mid 60s. Northeast winds around 5 mph in the evening, becoming light and variable.

Sunny. Highs in the upper 80s.

Mostly clear in the evening, then partly cloudy with a slight chance of showers and thunderstorms after midnight. Lows in the lower 70s. Chance of rain 20 percent.

Partly sunny. A chance of showers in the morning, then a slight chance of showers and thunderstorms in the afternoon. Highs in the upper 80s. Chance of rain 30 percent.

Partly cloudy. A slight chance of showers and thunderstorms in the evening, then a chance of showers after midnight. Lows in the upper 60s. Chance of rain 40 percent.

Partly sunny. A slight chance of showers in the morning. Highs in the lower 80s. Chance of rain 20 percent.

Partly cloudy. A slight chance of showers and thunderstorms after midnight. Lows in the mid 60s. Chance of rain 20 percent.

Mostly sunny. A slight chance of showers in the morning. Highs in the lower 80s. Chance of rain 20 percent.

Partly cloudy. Lows in the mid 60s.

Partly cloudy. Highs in the mid 80s.

Clear. Low temperature around 69F. Dew point will be around 67F with an average humidity of 82%. Winds will be 2 mph from the E.

Sunny. High temperature around 84F. Dew point will be around 68F with an average humidity of 71%. Winds will be 3 mph from the E.

Mostly clear. Low temperature around 71F. Dew point will be around 67F with an average humidity of 74%. Winds will be 5 mph from the SE.

Sunny. High temperature around 88F. Dew point will be around 69F with an average humidity of 67%. Winds will be 3 mph from the S.

Clear. Low temperature around 73F. Dew point will be around 69F with an average humidity of 72%. Winds will be 2 mph from the S.