Abstract:The main characteristics of the general atmospheric circulation in May 2021 is that the two polar vortex centers were in the Northern Hemisphere and stronger than usual. The circulation finished the transition from a three wave pattern to a four wave pattern and the 500 hPa geopotential height presented the distribution of a four wave pattern in middle high latitudes of Northern Hemisphere. The strength of Western Pacific subtropical high was stronger than that in normal years, and the South China Sea summer monsoon erupted in the sixth pentad. The monthly mean temperature was 16.9°C, 0.7°C higher than normal. The monthly mean precipitation amount was 74.8 mm, 8% more than normal. Six regional rainfall processes occurred in China this month. Meanwhile, several provinces were attacked by gales and hailstorm, including the tornadoes seen in Wuhan, Hubei Province and also that in Jiangsu Province, which led in economic losses and casualties to same degree. In addition, four dust sand events occurred in the northern part of China, making a wide range of impacts and being the most compared with such events in the same period since 2002. The drought maintained or developed in the provinces of Yunnan and Sichuan, but the drought condition in most parts of South China got relieved at the end of May.