Abstract:The main characteristics of the general circulation in May 2024 are that the polar vortex in the Northern Hemisphere was partially 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 had transformed from a three-wave pattern in winter into a four-wave pattern in summer, and the meridional degree of the Eurasian circulation was relatively high. The western Pacific subtropical high was stronger and located more westerly and northerly than that in normal years, while the south branch trough was weaker than usual. The monthly mean temperature across China in May was 17.7℃, 1.2℃ warmer than normal. The monthly mean precipitation was 69.5 mm, which is 1% less than normal. During this month, five regional torrential rain processes occurred in China, but the South China Sea summer monsoon erupted in the sixth pentad (May 26), 2 pentads later than the normal onset time in the fourth pentad in May. In addition, three severe convection weather events occurred this month, making the hit areas suffer from gales and hailstorm. Moreover, the northern part of China was troubled by two sand-dust events in this month.