The vast area of the People's Republic of China extends from 53° to 18°N and from 73° to 135°E in central and eastern Asia. It has a range of climates varying from tropical to cold temperate, and from high mountain to desert.
The country is often divided into China proper and the outer territories. China proper consists of the coastal regions fronting the Pacific and the valleys of the three great rivers: Huang He, Chiang Jiang, and Xi Jiang. This is the most productive and populated part of the country. The outer territories consist of the Manchurian Plain in the northeast, Inner Mongolia Autonomous Region in the north, the Xinjiang Uygur Autonomous Region in the northwest, and the Tibetan Autonomous Region (Xizang Zizhiqu) in the west. China has a long land border with Kazakhstan and Kyrgyzstan in the north and west, and on the south is bordered by Pakistan, India, Nepal, Myanmar, Laos, and Vietnam. Except in Inner Mongolia and Manchuria, these land borders traverse some of the most mountainous country in the world. This helps to make the climate of most parts of China very distinctive and throughout history has also tended to isolate China from outside influences of other kinds.
The climate of China proper and Manchuria is dominated by the great seasonal wind reversal called the Asiatic monsoon. From October until April winds tend to blow out from China and the heart of Asia under the influence of the great high-pressure system which develops in Siberia and central Asia at this time. From May until September or October, as the continent of Asia heats up, this area becomes one of low atmospheric pressure and winds are drawn into much of China, both from the Indian Ocean and the Pacific. These warm, moist winds bring most of the annual rainfall to Manchuria and China proper at this time. The Tibetan, Xinjiang Uygur, and Inner Mongolian autonomous regions, furthest removed from the influence of the sea, receive much less rain.
The second important control over the climate of China is latitude. While most of the country has warm to hot summers, there is a great difference in winter temperature both from north to south and from the western provinces to the coastal regions. North China, including Manchuria, has extremely cold winters of almost Siberian severity, while Inner Mongolia and Xinjiang Uygur share in this winter cold. Tibet, being a great upland plateau rimmed by some of the highest mountains in the world, has cool summers and very cold winters.
This monsoonal climate regime is so characteristic and dominant over most of the country that some climatologists have referred to the 'Chinese type of climate' to indicate a large seasonal range of temperature, a wet summer, and a dry winter. It has certainly been a factor in bringing about the cultural unity of China proper. Except in the far north of China, and in the outer territories, this warm, wet summer results in rice being the dominant food crop of the country.
This similarity of both cause and effect, however, should not be allowed to hide the fact that there are important differences of weather and climate, both from north to south and from the lowlands and river valleys of China proper to the desert and mountainous regions of the outer provinces. South and central China have a tropical or subtropical climate with no real winter cold, while north China, Manchuria, and the western provinces have a severe winter. Eastern China has abundant summer rain while the northern and western regions contain much desert and semi-desert.
For a more detailed description of the weather and climate the country is divided into the following major climatic regions: northeast China including Manchuria, central China, south China, southwest China, Tibet, Xinjiang Uygur and the western interior, and Inner Mongolia.
Northeastern China, including Manchuria
The tables for Shenyang in Manchuria and for Beijing are representative of conditions here. This region broadly consists of the great lowland area of the Huang He Valley, part of Inner Mongolia, and the whole of Manchuria. Winters are very cold with frequent light snow and much frost. The strong out-blowing winds often raise clouds of dust which are a troublesome feature of the weather. There is a rapid decrease in both winter and summer temperatures northwards so that in northern Manchuria rivers are frozen for four to six months. The extreme north of Manchuria has a significantly colder summer than Shenyang or Beijing and snow lies for between 100 and 150 days.
Summers are warm and humid over much of north China and may be rather uncomfortable. Summer rainfall is almost everywhere sufficient for cultivation but tends to be unreliable; in some years drought may be a problem. The most unpleasant features of the climate are the summer humidity and the cold, increased by wind chill in winter, so that warm winter clothing is very necessary.
The tables for Shanghai on the Coast and for Hangzhou, about 640 km/400 mi inland in the valley of the Chiang Jiang, are representative of this region, which has warmer summers than north China and milder winters.
Although the main rainy season is summer there is some rain throughout the year and the winter weather is more changeable than in north China. There are periods of wet weather, alternating with cold spells during which frost and snow occur; snow falls on about five to ten days a year. This variable winter weather is not unlike that experienced in parts of western Europe and the mid-Atlantic states of the USA. It is a consequence of frontal systems and depressions moving from west to east along a zone of convergence between cold Siberian air and warm air from the Pacific.
Summer weather is warm and usually humid as warm, damp air moves in from the Pacific; the heat and humidity are occasionally rather uncomfortable. The coastal regions occasionally receive very heavy rainfall from typhoons, or tropical cyclones, which intensify in the South China Sea and move northeastwards along the coast. The very strong winds associated with these disturbances are most severe in the coastal belt.
Farther inland in central China there is a region in the middle and upper Chiang Jiang valley, the basin of Sichuan, where winters are distinctly milder and summers receive rather less rain. This area has a more pleasant climate as winter snow and frost are less frequent and summer humidity is less uncomfortable (see the table for Chongqing).
This region is partly within the tropics and is the warmest and wettest part of the country in summer. Rainfall is very heavy between May and September along the coast and abundant inland. Winters are mild and frost almost unknown. The summer heat and humidity can be rather uncomfortable. Conditions are represented by the table for Hong Kong and Wuzhou inland. Conditions at Guangzhou and Macao are very similar. Typhoons are more frequent here and at their most violent and may bring very heavy rain and strong winds for a few days at a time to the coastal regions. Typhoons are most frequent from July to October.
Hong Kong consists of one major island, a number of smaller inhabited islands, and a portion of the mainland. Its total area is only 1,070 sq km/413 sq mi. Situated in 22°N, it is just within the tropics and has a similar monsoon climate to that of south China. Rainfall is particularly heavy from early May until late September, but some rain occurs in all months. Although occasional cold spells, lasting a few days, occur in winter, snow and frost are virtually unknown and the period from October to March is generally warm and dry.
Humidity is high during the rather hot, wet summer and the weather is often very sultry and oppressive. Particularly between July and September, typhoons, moving northwards from the South China Sea, bring heavy rain and very violent winds which can cause damage to property and loss of life. Although mainly dry, the months from February to April are rather cloudy and sunshine then averages only three or four hours a day, as compared with an average of six to eight hours a day during the months July to December.
This inland region along the border with Myanmar, Vietnam, and Laos is hilly and mountainous. Summer temperatures are somewhat moderated by altitude. Winters are generally warm to mild with much sunshine and very little rain. Only occasionally does cold air penetrate here from the north, bringing occasional frost at higher levels. Summers are wet at higher levels but in sheltered valleys the rainfall is not excessive. This region has the most pleasant weather and climate in China around the year (see the table for Mengzi).
This is a region of high plateaux and encircling mountains, situated in southwestern China. Its southern boundary includes the highest peaks of the Himalayas, such as Everest. Most of the region is above 3,700 m/12,000 ft, and some extensive areas rise above 4,900 m/16,000 ft. Winters are severe with frequent light snow and hard frost. Considering the altitude, summer temperatures are surprisingly warm in the daytime, but there is a very sharp drop in temperature at night. Most of the precipitation is rain during the summer, when moist air is drawn into the region by the Asian monsoon winds.
In the west and north of the region some winter precipitation falls as snow; but the permanent snowline is surprisingly high at about 6,600 m/20,000 ft. Apart from the low temperatures, strong winds, which accentuate wind chill, are the worst feature of the climate. The table for Lhasa shows conditions in the valleys and lower southeastern part of Tibet. For much of the year the air is very clear and sunshine is abundant.
Xinjiang Uygur and the Western Interior
This remote and sparsely populated region of Central Asia is almost entirely desert. It has a continental type of climate with cold winters and hot summers. The very sparse precipitation is well distributed around the year, with a winter maximum in some places; this is brought by weak depressions moving in from the west. Humidity is low throughout the year and the climate is generally healthy; the principal hazards are very low temperatures accompanied by strong winds in winter and occasional very high temperatures in summer. Climate varies locally depending on altitude; there are some high mountains on the border with Kyrgyzstan and Tibet, but extensive areas of interior lowland. The table for Kashi illustrates conditions in the west of Xinjiang Uygur at medium levels.
Situated to the north and east of Xinjiang Uygur, this is a region of mountain ranges and extensive semi-desert lowlands, including the southern portion of the Gobi Desert. It adjoins central Siberia and Mongolia. It has an extreme continental type of climate with very cold winters and warm summers. The sparse precipitation is well distributed around the year. The summers are somewhat cooler than Xinjiang Uygur, but winters are even colder, resembling those of Manchuria and north China. The ground is snow-covered for 100-150 days a year. See the table for Urumqi and the description of Mongolia.
Strong winds in winter and spring often raise great clouds of dust which are blown eastwards into north China. This is one of the more unpleasant features of the climate. The severe winters make warm clothing very necessary and wind chill may increase the feeling of cold. Sunshine amounts vary from five to six hours a day in winter to about nine in summer.
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