What kind of weather can we expect in early May for Bejing, Shanghai, and Xian?

May in Beijing is pleasant. Normally, the temperature remains around 10-25C (50-77F), very warm and even hot. There are usually less windy days and few sandstorms during this month. It also has proper rainfall.
Shanghai weather in May is warm, sometimes even hot. Pleasant sunny days are the majority. The average temperature ranges from 16~24C. It won't have much rainfall in this month.
In May, the temperature in Xian rises quickly. Sometimes it becomes as hot as summer with the temperature climbing up to 30 C, while sometimes the temperature may drop to 14C when it rains. It rains comparatively much during May.

well i cant help you that much but i hope i can help you a little. I only know about beljiong.In may it is supposed to be a little cold and cloudy. You should still wear a jacket.

Thank you, Wendy. This was very helpful