Yunnan with its complicated terrain has a diversified climate. It is divided, from north to south, into three climatic zones-- temperate, sub-tropical and tropical, distributed, from low to high terrain, over four regions -- the low, hot river valleys, mountain areas, and frigid highlands, forming a peculiar "three-dimensional" climate.
Yunnan's climate is characterized by small seasonal change in temperature, great difference in daytime temperature, and regional contrast between dry and wet seasons. Its mean annual temperature increases from 7 degrees Celsius. in the northwest to 22 degrees Celsius or more in the Yuanjiang River valley. It has abundant rainfall and a mean annual precipitation of 750-1,750 mm. The rainfall in the wet season of May to October accounts for 83% of the annual precipitation.