Best weather period of the year to make a full tour of China from mid/warm to sub-tropical zones ?

Generally speaking, it is a nice time for travelling around China at the beginning of May except the traffic crowds during the May Holiday. The weather gets warmer and warmer along the route from Beijing to Hong Kong. It is warm in Beijing, Xian, and Shanghai with proper temperature and rainfall, while it may be a bit hot in Guilin, Yangshuo, and Hong Kong with much rainfall. Anyway, you'd better pay close attention to the weather forecast when travelling around China.