China has a climate dominated by monsoon winds. It features clear temperature differences in most parts between winter and summer. In winter the northerly winds are cold and dry and in summer, southerly winds are warm and moist. Of course climates differ from region to region because of the country's extensive territory and complex topography. In the southeastern part south of the Nanling Mountains, rains are plenty and the temperature is high all year round. In the Yangtze and Huaihe river valleys in the central part, there are four distinctive seasons. In northeast China, summer is short but there is much sunshine, while winter is long and cold.
The climate in Beijing is of the continental type, with very cold and dry winters. The summers are hot. Winter usually begins towards the end of October. The summer months, June to August, are wet and hot with about 40% of the annual precipitation.
Summer is peak season, when hotels typically raise their rates and the Great Wall nearly collapses under the weight of marching tourists. The autumn months between September and October have the best weather and fewer tourists. Spring is less pleasant - not many tourists but lots of wind and dust. In winter, you'll have Beijing to yourself and many hotels offer substantial discounts, but it's an ice box outside.
Shanghai starts the year shivering in midwinter, when temperatures can drop below freezing and the vistas are gray and misty. Spring brings warmth; April to mid-May is probably one of the best time to visit Shanghai, along with autumn (late September to mid-November). in summer the hot and humid weather makes conditions outside uncomfortable, with temperatures sometimes as high as 40°in July and August.
Hainan Island enjoys a monsoon sub tropical AND tropical climate with annual average temperatures ranging between 18°C and 28°C and more than 300 sunny days per year.
April through June can be very hot and humid. Typhoons are a fact of Hainan Island Life with at least one per year typically between July and September.
This small island has two different climates, Haikou and its surrounding area is in the subtropical zone and Sanya is in the tropical zone, which is the main reason why Sanya is the top destination for the visitors coming to Hainan Island.
Hong Kong's climate is sub-tropical. November and December are the best months of the year with pleasant breezes, plenty of sunshine and comfortable temperatures. January and February are more cloudy and it is not uncommon for temperatures to drop below 10 C in urban areas.
March and April can also be very pleasant although there are occasional spells of high humidity. Fog and drizzle can be particularly troublesome on high ground which is exposed to the southeast, and air traffic and ferry services are occasionally disrupted because of reduced visibility.
May to August are hot and humid with occasional showers and thunderstorms, particularly during the mornings. Afternoon temperatures often exceed 31 C whereas at night, temperatures generally remain around 26 C with high humidity.
July to September are the months during which Hong Kong is most likely to be affected by tropical cyclones, although gales are not unusual at any time between May and November. On average, about 31 tropical cyclones form in the western North Pacific or China Seas every year, and about half of them reach typhoon strength (maximum winds of 118 kilometres per hour or more).