China has a continental and seasonal climate. Most parts are in the temperate zone but southern areas are in the tropical or subtropical zone while northern areas are in the frigid zone. Climates in different areas are complicated. For instance, northern Heilongjiang Province has a winter climate the year round without summer, while Hainan Island has a summer climate the year round without winter. Take look at this link to get an idea of the typical temperatures and rainfall you may expect in the major cities.
The rainy season occurs between March and April in southern and eastern China (e.g. Guilin, Suzhou, Hangzhou), from June until August in the west (e.g. Yunnan Province and Tibet), and between May and September for the areas near the Yangtze River (e.g., Chongqing and Yichang).
During these times severe rainstorms can cause landslides in Shangri-La and remote areas in Tibet which may interrupt essential services. Rural areas near the Yangtze River may be subject to flooding. Typhoons can occur during the wet season along the southern and eastern coasts.
You should monitor weather reports if travelling in affected areas. In the event of a natural disaster occuring, stay in touch with the local representative who should follow the advice of the local authorities.