The climate in Tibet is complicated and diversified. Overall, the Tibetan climate features frigid and dry air in the northwest and warm and humid in the southeast, forming climatic zones (southeast-northwest) such as the tropical, subtropical, plateau temperate, and plateau sub-frigid climatic zones. Tibet has thinner air, more sunlight, lower temperatures and less precipitation than other areas in China.
Tibet has a clear distinction between dry and wet days. Generally speaking, the months from October to April are a dry season while the months from May to September are a wet season. Rainfall is unevenly distributed in different places of Tibet. Rain usually falls at night. Annual precipitation is 5,000 millimeters in the lower elevations to the southeast de creasing gradually to a mere 50 millimeters in the northwest. Precipitation from October to April accounts for only 10 to 20 percent of the yearly total rainfall is concentrated in the period between May and September, accounting for about 90 percent o the yearly precipitation.
Daytime and nighttime temperatures vary greatly, despite low average temperatures and low annual temperature differentials. Average temperatures and peak temperatures for the hottest month in Lhasa and Shigatse are 10 to 15 degrees centigrade lower than in Chongqing, Wuhan and Shanghai at about the same latitude Annual temperatures in Lhasa, Qamdo, Shigatse and elsewhere in Tibet range 18 to 20 degrees centigrade over the year At elevations in excess of 5,000 meters in Ngari Prefecture, daytime temperatures in August climb above 10 degrees centigrade, only to fall below zero at night. Seasonal precipitation is disproportionately distributed throughout the region.
Tibet boasts more solar radiation that any other part of China, about 100 percent or one-third more than in plains at the same latitude. In addition, Tibet enjoys longer duration of sunshine. Both the annual average temperature and the highest temperature in Lhasa and Shigatse are 10-15 degrees Centigrade lower than in Chongqing, Wuhan and Shanghai. In the Ngari area, some 5,000 meters above sea level, the temperature in August reaches 10 degrees Centigrade or higher during the day, but falls to below zero at night. Seasonal precipitation is disproportionately distributed throughout the region
There exists great difference in climate between southern and northern Tibet. Under the impact of warm humid air currents from the Indian Ocean, the valleys in southern Tibet enjoy warm and wet weather, with the annual average temperature being 8 degrees centigrade. The northern Tibet Plateau enjoys a continental climate, with the annual temperature staying below zero. However, the icing period extends over the bulk of the year. March-October is the ideal season for visits and June-September the best season of all. Recent years have seen huge influx of visitors to Tibet in winter.
The central Tibet, including Lhasa, Gyantse, Shigatse and Tsedang, generally has very mild weather from April to November, though July and August can be rainy - these two months usually see around half of Tibet's annual rainfall. October and November often bring some dazzling clear weather and daytime temperatures can be quite comfortable at Tibet's lower altitude.
The coldest months are from December to February. It is not impossible to visit Tibet in winter. The low altitude valleys of Tibet (around Lhasa, Shigatse and Tsedang) see very little snow.
Spring does not really get under way until April, though March can have warm sunny days. Here is some more specific Tibet weather information in different areas:
* 'C is in Celsius. 'F is in Fahrenheit.