Below is a list of O Fallon MO zip codes. For your research we have also included O Fallon Area Code, Time Zone, UTC and the local Saint Charles County FIPS Code. Each O Fallon Missouri zip code has a center Longitude / Latitude point (the O Fallon center is -90.708999633789 / 38.787700653076). For your convenience we have also indicated if that zip code in O Fallon observes Daylight Savings time.