The following are the main characteristics of the general atmospheric circulation in October 2012. There was one weak polar vortex center in the Northern Hemisphere. The circulation presents a four wave pattern in middle high latitudes. The meridional circulation is more obviously, the south branch trough and the West Pacific subtropical high are stronger than normal years’. The monthly mean precipitation is 29.1 mm, and is 18.9% less than normal. The monthly mean temperature is 10.3℃, and is equivalent to normal. There were four cold air processes affecting China. Typhoon Son Tinh made landfall in South China and brought a heavy rainfall process. The rainy weather in Southwest China and the autumn drought in South China are continued, but improved in both the mid and late October. Parts of the middle and east of China suffered from fog disasters. The individual parts of China suffered from low temperature freezing damage, local flooding and hail disasters.