The main characteristics of the general atmospheric circulation in January 2021 are as follows. Polar vortex was a dipole pattern in the Northern Hemisphere. The atmospheric circulation presented a great meridionality in the mid-high latitudes in Eurasia. The East Asian trough was stronger to the west, and the southern branch trough was weaker in this month. The monthly mean precipitation over China was 5.6 mm, 58% lower than normal (13.2 mm), which is the fourth lowest since 1961. The monthly average temperature was -4.5℃, which is 0.5℃ above the normal. Totally, there was one strong cold air process, two dust weather processes and one largescale fog-haze event in this month. During 4-7 January, a strong cold air process occurred in central and eastern China, characterized by wide range of influence, significant low temperature extremes and long duration of strong winds in northern China.