The main characteristics of the general atmospheric circulation in October 2015 are as follows: Over the Northern Hemisphere, there was one polar vortex center, which is more intense than usual. In the midhigh latitudes,the circulation presented a fourwave pattern. The West Pacific subtropic high system was stronger than usual, and its ridge extended to west obviously. The monthly mean precipitation was 39.5 mm, 10.3% higher than the climatological mean (35.8 mm). Meanwhile, the monthly mean temperature was 11.0℃, which is 0.7℃ higher than its climatological mean (10.3℃). In the Northeast, the Beijing-Tianjin-Hebei Region and the east of Northwest, 62 stations observed extrem temperature drop events. Four severe rainfall processes occurred during this month. The central and western part of Guangdong, and the east part of Guangxi went through a torrential rain process from 3 to 6 October. During this month, four cold air processes affected China. Central and eastern China suffered from three severe fog and haze events. On 4 October, Severe Typhoon “Mujigae” made landfall in Guangdong with intensity equal to the historic record, causing great losses.