The Facts About O'fallon Attraction RevealedTable of ContentsMore About O'fallon LocationO'fallon Attraction for BeginnersO'fallon Weather for DummiesGetting My O'fallon Weather To WorkO'Fallon is a city in St. Clair County, Illinois, which was established in 1854. O'Fallon's name comes from Colonel John O'Fallon, who was a wealthy gent from St. Lo