What is the reason why Yunnan has the climate characteristics from Hainan Island to Heilongjiang?

The main reason is that Yunnan has diverse topography and great differences. Yunnan Province is a province dominated by plateaus and mountains, with extremely diverse landform types, including plateaus, plains, mountains, Zhongshan, low mountains, hills, basins and river valleys. Among them, mountainous areas account for 84%, plateau hills account for 10%, and basins and valleys account for 6%. The topography of Yunnan province is similar to that of the whole country, with high northwest and low southeast. The highest peak in the province is Meili Snow Mountain in Deqin County, Diqing Tibetan Autonomous Prefecture in the northwest, with an altitude of 6740 meters. The lowest point is red river valley, Hekou County, with an altitude of 76.4 meters. So the temperature is cold at high altitude and the climate of the earth is hot at low altitude.

Another reason is that Yunnan, like most parts of China, belongs to monsoon climate type. Controlled by the summer monsoon, it is hot and humid, similar to the climate of Hainan Island. Controlled by the winter wind, it is cold and dry, similar to the Heilongjiang River Basin.