10-Day Weather Forecast - O'Fallon, IL

Mostly cloudy this morning then becoming mostly sunny. Much cooler with highs in the upper 30s. Temperature falling into the lower 30s this afternoon. Northwest winds 15 to 20 mph with gusts up to 35 mph.

Clear. Much cooler with lows around 18. Northwest winds 10 to 15 mph. Gusts up to 30 mph in the evening.

Sunny. Highs in the mid 30s. Northwest winds 5 to 10 mph becoming west in the afternoon.

Mostly cloudy. A chance of snow mainly in the evening. Lows in the upper 20s. Southwest winds 10 to 15 mph with gusts up to 25 mph. Chance of snow 30 percent.

Mostly sunny in the morning then becoming mostly cloudy. Not as cool with highs in the mid 40s. West winds 15 to 20 mph with gusts up to 30 mph.

Mostly cloudy. A slight chance of snow in the evening. Lows around 20. Chance of snow 20 percent.

Partly sunny. Much cooler with highs in the upper 20s. Wind chill values as low as 5 above.

Partly cloudy. Lows around 10 above. Highs in the mid 20s. Wind chill values as low as 5 below.

Partly cloudy. Lows around 10 above. Highs in the mid 20s. Wind chill values as low as 5 below.

Partly cloudy. Lows around 15. Highs in the lower 30s. Wind chill values as low as zero.

Partly cloudy. Lows around 15. Highs in the lower 30s. Wind chill values as low as zero.

Mostly clear. Lows 10 to 15. Wind chill values as low as zero.

Mostly sunny. Highs in the mid 30s. Wind chill values as low as 5 above in the morning.

Clear. Low temperature around 24F. Dew point will be around 14F with an average humidity of 61%. Winds will be 5 mph from the S.

Mostly sunny. High temperature around 42F. Dew point will be around 25F with an average humidity of 61%. Winds will be 6 mph from the S.

Mostly cloudy with a slight chance of rain. Chance of precipitation 25%. Low temperature around 32F. Dew point will be around 29F with an average humidity of 80%. Winds will be 3 mph from the S.

Cloudy with a slight chance of rain. Chance of precipitation 30%. High temperature around 43F. Dew point will be around 33F with an average humidity of 74%. Winds will be 4 mph from the SE.

Cloudy with a chance of rain. Chance of precipitation 45%. Low temperature around 37F. Dew point will be around 35F with an average humidity of 86%. Winds will be 2 mph from the S.