Introduction:Iran is located in the south-west of Asia and is in the arid belt of the world and about 60% of the extent of the country is mountainous and the remaining part (1/3) is desert and arid land. Climate of the country can be divided into three main categories: -Warm temperate, rainy with dry summer in a narrow strip in the north, -Dry, hot desert in the central plateau, -Dry, hot steppe covering the rest of the country. Then, it could be so difficult to predict climate change over whole of the country.