Fremont County is a county located in the U.S. state of Iowa. As of the 2020 census the population was 6,605, making it the state's seventh-least populous county. The county seat is Sidney. The county was formed in 1847 and named for the military officer John C. Frémont.

The Midwestern United States experienced major floods in the spring of 2019, primarily along the Missouri River and its tributaries in Nebraska, Missouri, South Dakota, Iowa, and Kansas. The Mississippi River also saw flooding, although starting later and ending earlier. The 2019 January-to-May period was the wettest on record for the U.S., with multiple severe weather outbreaks through May in the Midwest, High Plains, and South exacerbating the flooding and causing additional damage. Throughout late May and early June, rain in Iowa, Illinois, and Missouri caused every site on the Mississippi River to record a top-five crest. At least three people in Iowa and Nebraska died.