The climate changes observed in recent years as an increase in the average air temperature influence the microclimatic conditions in dairy barns not only in summer but also in winter. The heat emitted by cows, the orientation of buildings to the cardinal points and farm layout have substantial effect and are additional factors influencing the microclimate in the barns with curtain sidewalls. The aim of the present studies was to determine the effect of atmospheric air temperature and relative humidity on the selected parameters of the indoor microclimate in two neighboring freestall barns in winter. The air temperature and relative humidity sensors were positioned in the barns (A, B) and outdoors. The obtained results were compared with each other. The indoor air temperature recorded in two barns was higher than the outdoor temperature by an average of 2.4°C and 2.8°C, respectively. The greatest difference between the average indoor and the outdoor air temperature was 4.9°C. Daily analysis indicated that in warm days, the patterns of the air temperature and relative humidity changes were similar in both barns. In turn, during cold days, when the outdoor air temperature was below 0°C, there was a difference in temperature between both barns, which could result from the position of the buildings towards cardinal points and the heat emitted by cattle influencing the air temperature in the barn. The points where the temperature difference was the highest were located in the leeward part of the building, which was additionally sunlit during the midday hours. Thus, it is recommended to estimate the airflow velocity and sun exposure in different zones of the barn. This would also help to establish the guidelines for the design of new barns in the context of architectural and spatial solutions.