St. Louis Region
The southern tier drops into the Missouri River floodplain
Warren County's southern edge meets the Missouri River bottoms near Marthasville and Dutzow, so flood-zone status is a real buying question there even though the uplands around Warrenton are dry.
South of the I-70 uplands, Warren County drops toward the Missouri River. Around Marthasville and Dutzow, the land slips into the river bottoms. A parcel there can have a very different flood story than a place up by Warrenton.
For a buyer, the flood map is part of the first look, not a late surprise. A FEMA flood-zone designation can affect flood-insurance expectations, lender questions, and what kind of building homework comes next. One dry season does not tell you where the river has room to go.
Use the FEMA Flood Map Service Center for the specific address, then ask local questions about access roads, low ground, and how the bottoms behave in wet years.
References
Where this fits: this note belongs to Warren County. See every local note for the county on its page.