May marks the beginning of China's peak travel season. The weather now is very pleasant with plentiful sunshine and mild nights. It is the ideal time of the year in most of China, that stretch of warm weather before the heat and humidity of summer set in. May is one of the best times for traveling and sightseeing in China, the other being September and October. The countryside has greened up and flowers are in full bloom. It is not uncommon to see families and friends drive to the country to spend their weekends.
In North China, spring is at its best. Blue sky may be seen in cities which rarely have blue sky during the rest of the year, such as Beijing. May is also one of the best times to visit the Great Wall. In May, when trees and plants turn green, the wall wanders among lush vegetation. The summer crowds have not yet arrived, so you may have time to have the wall to yourself.
Central and South China is still very humid. The height of the rainy season begins in regions south of the Yangtze River. The Chinese called this rainy season "梅雨季节", méiyǔ jìjié (the monsoon). It usually lasts for one or two months and ends in late June. Shanghai and Hong Kong in May and June reach an average high of about 27°C (80°F), with humidity to match.
The North: It is comfortably warm during day and cool at night. Short-sleeve T-shirt or shirt is enough for day time. Bring along a jacket for cool evenings.
Central: It is comfortably warm during day and cool at night. Short-sleeve T-shirt or shirt is enough for day time. Bring along a jacket for cool evenings. Carry an umbrella.
The South : It is quite hot with highs in the high 20s °C (80+ °F). Shorts are enough. But it may become cool at times, so you may need to bring a sweater. Rain gear such as an umbrella, but also sun glasses and sun cream, are recommended.