Abstract:The main characteristics of the general atmospheric circulation in May 2023 are that the polar vortex in the Northern Hemisphere was mono-polar with stronger intensity than usual. The 500 hPa geopotential height presented the distribution of a four-wave pattern in middle-high latitudes of the Northern Hemisphere, which means that the circulation have transformed from a three-wave pattern in winter to a four-wave pattern in summer. The Western Pacific subtropical high was stronger than that of normal years. The monthly mean temperature across China was 16.3℃， 0.2℃ lower than normal. The monthly mean precipitation was 57.8 mm, 18% less than normal. During this month five torrential rainfall processes occurred in China. After the onset of the South China Sea summer monsoon in the third pentad, precipitation occurred in southwestern China， alleviating the drought in Yunnan Province. In addition, China experienced five severe convection weather events, making local areas suffer hail disasters. Besides, three sand-dust events were seen in northern China.