The 2014 North American cold wave was an extreme weather event beginning in January that was part of an unusually cold winter affecting parts of Canada and the Eastern United States, east of the Rocky Mountains. Freezing weather conditions have gripped a large portion of the US and Canada, with temperatures reaching extreme lows such as-35° C in North Dakota and -26° C in Minneapolis, Indianapolis and Chicago. At least 12 deaths are blamed on the unusually cold temperatures. We think this symptom is related with our studying and would like to research about it.