This study was conducted to determine the effects of vent configuration and external wind speed on three-dimensional distribution of air temperature in a naturally ventilated multi-span greenhouse using wind tunnel experiments. The experiments were conducted with the scale models in a wind tunnel with four different vent configurations and at four external wind speeds ranging from 0 to 3 m/s at full scale, with 1 m/s increments. Three dimensional temperature distributions were analyzed and the airflow patterns were observed based on temperature distributions. The highest air temperatures were found to be in spans close to the leeward side vent when the side vents were closed at zero wind speeds in the case when the roof vents were fully open and side vents were closed. The air temperature, measured by thermocouples, was higher on the windward side of the greenhouse than on the leeward side for all wind speeds when only roof vents were used. The distribution of air temperature was more uniform when both side and roof vents were used. As the wind speed increased, the average internal air temperature decreased for all cases. Contribution of side vents for greenhouse ventilation and reduction of air temperature were significant for the particular greenhouse design used in this study.