Abstract:During the winter 2012, Beijing suffered 3 high influence weather events: lasting cold weather in December, continuous fog and haze in January 2013 and freezing rain on 31 January 2013. The three events brought many adverse effects to Beijing, and have become the focus of the whole society. Using conventional observation data and the atmospheric component data， the causes for the three extreme events are studied, and the intrinsic relations among them are analyzed. The results show that: (1) Frequent cold air activities and intensity are the main cause for the continuous low temperature event, which leads to continuous fog, haze and freezing rain. (2) From the atmospheric stability analysis, we find that the horizontal stability of cold and warm advection is corresponding to the level of pollutant concentration; and, vertically, the low temperature in boundary layer and dry warm advection to the top of the boundary layer play an important role for the accumulation of haze. (3) Low temperature in low level and warm air in the sky contribute to a freezing rain stratification. Therefore, one extreme weather event that may lead to other extreme weather events should be concerned about.