High temperature during hot summer months is associated with poor animal reproductive performance. The study aimed to explore the seasonal thermal impacts on the bucks fertility. Twenty healthy mature bucks were used in this study. Depending on environmental temperature, bucks were equally divided into two groups: Winter season (n=10) and Summer season (n=10). Scrotal width, circumstances, length, and diameter of right and left testicles, as well as length of right and left testicles were evaluated. From each goat, the semen samples were collected once a month during summer and winter seasons. Immediately after collection of semen, volume of semen, pH, concentration, motility, live sperm percentage, sperm morphology (1st abnormalities and 2nd abnormalities), sperm viability and intact acrosome were evaluated. Plasma triglyceride, cholesterol, glucose and testosterone concentrations were monitored. The results revealed that scrotal circumstances, length, diameter of right and left testicles, and length of right and left testicles were lower (p<0.05) in summer season than winter. Scrotal width was not different between the seasons. The Semen volume, concentration, motility, percentage of live sperm and intact acrosome in the summer season were lower (p<0.05) compared to winter. Semen pH, 1st abnormalities and 2nd abnormalities in summer season were higher (p<0.05) compared to winter. Plasma triglyceride, cholesterol, glucose and testosterone concentrations were decreased (p<0.05) during summer than in winter. Histopathological lesions were found in summer group in comparison to winter. In conclusion, the findings confirm that a high temperature during summer conditions negatively affects bucks semen quality.