In recent years, significant temperature increase all across of the world draws attention and climate regimes are shifting in different parts of the world. By the reason of these climatological changes, a study was conducted in Gediz Basin/Turkey, where agricultural production has an important place. In the study prepared, twelve GCMs were utilized under RCP4.5, RCP6.0 and RCP8.5 scenarios of 5th Assesment Report of IPCC for the period 2015-2050. The statistical downscaling methods were employed and the projections were derived right after applying weighted-averaged ensemble mean by Bayesian Model Averaging method and bias correction by equidistant quantile mapping method. The temperature-based potential evapotranspiration formulas were modified in accordance with Penman-Monteith method and the aridity indexes were calculated by UNEP (1992). According to the projections, the mean annual temperature increases between 1.5℃ and 2.2℃ and mean total annual potential evapotranspiration increases between 5% and 8% are foreseen in Gediz Basin for the near future. It is foreseen that semi-arid climate regime may predominate over the region for all of the RCP scenarios under the increasing dryness in basin climate. In addition, it was obtained in the study that sub-humid climate state occurance for all of the regions included by the basin may be unexpected in the future for RCP8.5 scenario. The presence of semi-arid climate conditions may be more potent with the increasing trend of radiative forcing over time.