Longnan is in southern Gansu province bordering Shaanxi in the east and Sichuan in the south. It is called Gansu's southern gateway and gateway to
the northwest. The major geographic features in Longnan are the Qinba Mountains in the east, the Loess Plateau in the north, and the Tibetan Plateau in the west. It is part of the Central Han basin in the east and the
Sichuan basin in the south. Elevations range from above sea level. The three major rivers in Longnan are the
Bailong, the
Baishui, and the
Jialing. Besides these major rivers there are more than 3800 streams and creeks. The annual flow from all of these rivers and streams is more than 28 billion m3. The area of the prefecture is . Longnan has a temperate,
monsoon-influenced
semi-arid climate (
Köppen BSk/BSh, depending on the source definition), with cool and very dry winters and hot, moderately humid summers. Due to the protected valley location and the southerly location in the province, the area is one of the warmest in Gansu, with annual temperatures ranging from . The annual precipitation is , while there are between 160 and 280 frost free days. With monthly percent possible sunshine ranging from 34% in September and October to 53% in December, the city receives 1,850 sunlight hours annually. Two-thirds of the annual rainfall occurs from June to September. At Wudu, the monthly 24-hour average temperature ranges from in January to in July, the annual mean is , and the annual precipitation is . ==History==