Abstract:The main characteristics of the general atmospheric circulation in May 2014 are as follows: There is one polar vortex center in the Northern Hemisphere, and the intensity is 524 dagpm, 4-6 dagpm stronger than normal years. The 500 hPa geopotential height presents distribution of a four wave pattern in high latitudes of Northern Hemisphere, and the most areas in the eastern region of China are controlled by west air flow, causing more short wave trough activities. Subtropical high is more westward and northward than normal, which is the main cause for the extreme precipitation seen many times in South China. Monsoon starts later than normal years over South China Sea. The monthly mean temperature is 16.5℃, 0.3℃ higher than normal. The monthly mean precipitation amount is 73.8 mm, which is 6.2% more than normal. The main weather characteristics in this month is as follows: Torrential rainfalls occur in Southern China frequently, and extreme high temperatures appear in Northern China.