The main characteristics of the general atmospheric circulation in December 2018 are as follow. There was one polar vortex center in the Northern Hemisphere, located in the north of Greenland. The Eurasia midhigh latitude circulation presented a troughridgetrough pattern and a great meridionality. The south branch trough was strong, lying around 90°E averagely. The subtropical high stayed more westward than in normal years. The monthly mean precipitation over China was 18.7 mm, which is 73.1% higher than normal. The monthly mean temperature over China was -3.8℃, 0.6℃ lower than normal (-3.2℃). Two largescale rainfall, three cold air, and two foghaze processes occurred in December. From 5 to 11 December and from 27 December 2018 to 1 January 2019, due to the influence of cold wave, two largescale lowtemperature rain and snow processes hit most areas of central and eastern China with lowest temperature breaking historical extremes in many places.