Recently, achieving outdoor thermal comfort has attracted considerable attention in many studies in regions with hot and humid climates. Sun sails have been used as a traditional street-shading strategy in cities to improve outdoor thermal comfort, but their advantages in achieving thermal comfort in school courtyards remain unexplored. This study improves thermal comfort in school courtyards by studying the effect of the sun sail-shading strategy. A case study using the sun sail-shading strategy in El-Safwa School courtyard in Port Said, Egypt, is simulated during school time. Field measurements were conducted in specific locations in the courtyard. Microclimate models were simulated using ENVI-met V4.4.5 and Rayman 1.2 software. Several proposed cases have been studied based on the courtyard shading coverage ratio varying from 0% to 100% shaded with black sun sails. Hence, by adding 60% or above sun-sail shading in the school courtyard, the simulation results revealed a reduction in the air temperature (Ta), with an average difference of 0.5 degrees C, reduction in the average predicted mean voted (PMV) values above 0.6, and reduction in the mean radiant temperature (Tmrt) average values in most of the receptor points (approximately more than 20% reduction). The analyzed results of the physiological equivalent temperature (PET) and standard effective temperature (SET) showed the futility of using 40% sun sail-shading in the school courtyard, and the proper court coverage ratio to use is 60%.