Abstract:The main characteristics of the general atmospheric circulation in December 2015 are as follows: There is one polar vortex center in the Northern Hemisphere, located near Greenland. The Eurasia mid high latitude circulation presents the trough ridge trough pattern. The south branch trough behaves actively, lying around 90°E averagely. The subtropical high is stronger and has larger area than normal years. The monthly mean temperature over China is -2.1℃, 1.1℃ higher than normal (-3.2℃). The distribution of precipitation is inhomogeneous. Large scale rainy weather appears in the southern part of China. The monthly precipitation in the south of the Yangtze River and South China is 100-200 mm, and for the whole country it is 24.1 mm, 1.3 times more than normal (10.5 mm), which is the maximum value for the corresponding periods since 1951. There are three cold air processes, three major rainfall processes and two large scale fog haze weather processes during this month, of which the fog haze event from 19 to 25 December is characterized by long duration, large scale and heavy air pollution, and the haze affected area is the largest in 2015.