Hourly ambient temperature data were collected as part of an effort to empirically evaluate the Upper Mississippi River System inundation model. The goal of this sampling effort was to document inundation through space and time at a limited number of sites but across the range of flow conditions experienced throughout the 2017 growing season. We used temperature data loggers (Onset HOBO Pendant Temperature Data Loggers, model #UA-001-08) to record hourly ambient temperatures at the floodplain’s surface for subsequent analysis of hourly and diurnal flux patterns that would indicate likely submergence. Temperature loggers were deployed in two separate sites within six study segments (Pools 4, 8, 13, 26, La Grange, and a section of the Open River); three sites were used in Pool 26 due to the complexity of the segment. Sites were selected to represent areas expected to exhibit contrasting levels of model performance due to model assumptions regarding hydrologic coupling. Temperature loggers were programmed to record hourly observations and were deployed along three parallel transects at each site. Transects were oriented orthogonal to the water’s edge and traversed the site’s local elevation gradient. Five loggers per transect (total of 15 per site) were installed along the ground using spacing designed to capture the full range of elevational change. Two additional loggers were installed as controls at most sites to monitor ambient air and water temperatures. Loggers remained in the field between 87 and 120 days across depending on logistical, weather, and personnel constraints of assisting field crews. Logger temperature records were downloaded upon retrieval from the field.