The main characteristics of the atmospheric circulation in the winter of 2018 (from December 2018 to February 2019) are as follows. The polar vortex was characterized by a monopole pattern, which centered over the Arctic Ocean to the Eurasian side. In December, the atmospheric circulation was featured by great meridional gradient over middle and high latitudes of the central and eastern Asia, which was favorable for the southward of the cold air. From January to February 2019, the meridional gradient decreased, middle and high latitudes gave first place to zonal circulation, the cold air was weakened, and sea fog processes in the eastern and southern sea areas were increasing. There were 17 gale processes above 8 grade over offshore areas of China, including 13 produced by cold air, two jointly by cold air and extratropical cyclone, one jointly by cold air and tropical cyclones, and one by extratropical cyclone. There were 14 rough sea wave processes above two meters and 64 days were with wave processes above two meters. Ten obvious sea fog processes occurred over offshore areas, mainly nearby Beibu Gulf from night to morning. The sea surface temperature differences between southern and northern sea areas were between 21 ℃ to 28 ℃ and sea surface temperature generally presented a declining trend. Three tropical cyclones were active over western North Pacific and the South China Sea.