O'Fallon is located in Missouri. O'Fallon, Missouri has a population of 89,012. O'Fallon is more family-centric than the surrounding county with 37% households with children. The county percentage for households with children is 32%.
The median household income in O'Fallon, Missouri is $89,601. The median household income for the surrounding county is $85,936 compared to the national median of $66,222. The median age of people living in O'Fallon is 37.9 years.
The average high temperature in July is 88.3 degrees, with an average low temperature in January of 18.4 degrees. The annual precipitation is 38.64.