Climates are constantly changing on a temporal and spatial scale, so they are not static. In recent years, global warming and changes in climate have shown more and more effects on the hydrological cycle and water resources, and their effects have become so noticeable that they hinder sustainable life. For this reason, the studies on the investigation of the main causes of the observed changes in the climate, the evaluation of climate change as a process and the determination of the effects that will emerge, have increased over time. In the present study, the homogeneity of annual and seasonal temperature series in Hirfanli Dam basin were examined by using the Pettitt Test (PT), and the trends were examined with the Spearman’s Rho (SR) test and Mann Kendall (MK) test. Hirfanli Dam basin, which is located in the semi-arid climate region where climate change can be seen due to its location, was chosen as the study area. The temperature data of the Gemerek, Kayseri, Kirsehir, Nevsehir, Sivas and Zara meteorological stations in the basin between 1965 and 2017 were analyzed. It was noted that summer temperatures increased throughout the basin. Significant trends to increase were also detected inspring and autumn. The trend to increase was statistically significant at a 95% confidence level in all stations except for the Zara in terms of annual temperatures. Trend maps were prepared for the basin by using the results obtained here and the Geographical Information Systems. It was reported that the tendency to increase in annual temperature series was because of the increase in summer temperatures at intense levels throughout the basin.