The most pleasant months of the year for O'Fallon are May, September and October. In O'Fallon, there are 3 comfortable months with high temperatures in the range of 70-85°. July is the hottest month for O'Fallon with an average high temperature of 89.2°, which ranks it as one of the hottest places in Illinois. January is the snowiest month in O'Fallon with 3.8 inches of snow, and 4 months of the year have significant snowfall. July is the most humid month, though humidity is low for most of the year.
Today's Weather - O'Fallon, IL
12 AM PST
|7 DAY FORECAST||DESCRIPTION||HIGH/LOW||WIND|
|This Afternoon||Mostly Sunny||84° / 66°||S 6 mph|
|Friday||Slight Chance Showers And Thunderstorms||86° / 67°||S 3 to 9 mph|
|Saturday||Sunny||90° / 71°||S 3 to 8 mph|
|Sunday||Slight Chance Showers And Thunderstorms||91° / 74°||S 6 to 14 mph|
|Monday||Chance Showers And Thunderstorms then Mostly Sunny||94° / 75°||S 10 mph|
|Tuesday||Slight Chance Rain Showers then Slight Chance Showers And Thunderstorms||94° / 74°||SW 8 mph|
|Wednesday||Chance Rain Showers||93° / 72°||SW 8 mph|
Average Monthly High and Low (°F)
Hot, Freezing, Rainy, Snowy Days: O'Fallon
YOU SHOULD KNOW
Many people confuse weather and climate but they are different. Weather is the conditions of the atmosphere over a short period of time, and climate is how the atmosphere is over long periods of time.
Weather is how the atmosphere is behaving and its effects upon life and human activities. Weather can change from minute-to-minute. Most people think of weather in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility, wind, and atmospheric pressure.
Climate is the description of the long-term pattern of weather in a place. Climate can mean the average weather for a particular region and time period taken over 30 years. Climate is the average of weather over time.