Placement of temperature/humidity data loggers inside the storage bags provided new information about the changes occurring in response to daily environmental conditions. The diffusivity of heat through bulk maize is influenced by the moisture content and porosity (Kustermann et al., 1981). The diurnal change in the environmental temperature resulted in cyclic heating and cooling of the grain; however, the center of the grain mass, where the data logger was located, never reached equilibrium with the outside temperature. These temperature characteristics where not impacted by the type of storage bag or location. The hermetic seal of the PICS bags shielded the grain from changes in the external relative humidity, resulting in little impact on the RH within the grain mass or in grain moisture content. Within the woven bags, the data loggers did not detect daily changes in external RH; however, the RH gradually increased with time as did the grain moisture content. At the Arkansas location, during a period in September when the external RH was low resulted in a decline in the internal RH. Stored grain can exchange moisture with the environment and reach an equilibrium point (Pixton and Warburton, 1971). Williams et al. (2014) observed that low (29%) RH resulted in the drying of grain stored in woven bags but not PICS bags. We speculate that the September period of lower RH in Arkansas contributed to the lower final moisture content of the grain compared to grain in the Indiana experiment.