The objective of this pilot study was to determine how the micro-environment trailers transporting market-weight pigs’ change during different transport events in Iowa during warm weather. This study was conducted using 4 trailer loads carrying 680 mixed sex market weight (average 128 kg) pigs from commercial finishing facilities to a commercial processing plant all in Iowa. Data loggers were placed in 4 locations inside the trailer and a fifth data logger was placed on the outside of the trailer close to the cab of the truck on the driver’s side. Events of interest were loading, transport, wait time and unloading. Data from the logger placed on the outside of the trailer was used as a covariate in the regression. PROC REG of SAS was used to calculate the R2 value for temperature and relative humidity. Density, outside temperature or relative humidity, and time (minutes) were used as covariates in the models. Graphs were produced using the predicted values from SAS. Temperature increased during all events. Relative humidity increased during loading, but decreased during all other events. During loading, temperature inside the trailer increased by < 1°C and relative humidity increased by ~ 1.5 %. During transport, temperature inside the trailer increased by ~ 10 °C whereas relative humidity decreased by ~ 23 %. During wait time at the plant and unloading, temperature inside the trailer increased by ~ 9 °C. During wait time at the plant, relative humidity inside the trailer decreased by ~ 11 %. During unloading, relative humidity inside the trailer decreased by 5 % whereas temperature increased ~ 8 °C. In conclusion, during warm weather, temperature increased during all transportation events. Therefore, it is important to manage the internal trailer environment to meet the pigs’ thermal comfort zone during transportation.