In this research, 15 meteorological stations located in western Anatolia in Turkey were investigated for determining temperature properties. The vegetation season has been determined according to days when the daily temperature was greater than or equal to 8 degrees C. The research area has 3 different vegetation durations as longer (more than 225 days in the western and southern parts), moderate (210-220 days in plateaus around Usak, Gediz and Demirci), and shorter (180-195 days in the eastern part and less than 180 days in mountainous areas). Then, the vegetation has been reinvestigated according to climate change scenarios (RCP 4.5 and 8.5). For this purpose, the daily mean temperatures were raised by 2.6 degrees C and 4.8 degrees C for RCP 4.5 and RCP 8.5, respectively. In the reinvestigation period, the vegetation period will increase about 15-20 days or over 40 days according to RCP 4.5 and 8.5, respectively. Along with the increase in temperature throughout the research area, growing seasons will be significantly affected, beginning and ending dates of vegetation would shift. Owing to climate change effects, mountainous areas may be affected more than low altitude areas. As a conclusion due to the result of increasing temperature, plant development and distribution will be affected, and new plant species may occur.