Abstract:The main characteristics of the general atmospheric circulation in December 2024 are as follows. In the Northern Hemisphere, the polar vortex was distributed in a dipole pattern, and the mid high latitudes of Eurasia had a pattern of two troughs and one ridge. The western Pacific subtropical high was abnormally westward, and the Indo Myanmar trough was weak. Such a circulation pattern was not conducive to the occurrence of precipitation in China. In December, the average precipitation was only 5.3 mm, 55.5% less than normal, ranking the fifth lowest for the same period in history. There was scarce rain and snow in the central and eastern part of China. The number of snowfall days in Beijing, Tianjin and Liaoning was the lowest on record for the same period. Precipitation in Guangdong, Guangxi, Jiangxi, Fujian and other places was reduced by more than 80%, resulting in moderate to severe meteorological drought. The national average temperature was -2.9℃, 0.1℃ higher than in the same period of the normal years. Cold air was active during the month, and four cold air processes appeared, among which the strong cold air from 2 to 3 December led to heavy snow to blizzards in the northeastern part of Heilongjiang, the northeastern part of Inner Mongolia, the northwestern part of Xinjiang and other places. From 28 to 29 December, a wide range of cooling appeared over China, and the temperature in the south to Yangtze River, the eastern part of South China and other places dropped over 12℃ as the consequence of strong cold air. Gale force winds frequently appeared in northern China during the month, and sand dust weather were observed in some local areas of Inner Mongolia, Gansu and Ningxia. Finally, the overall air diffusion conditions across the country were relatively favorable in this month, and the number of fog haze processes and their intensity were clearly weaker than in the same period of the past decade.