From RealClimate, and referring to article in Lancet :

Guest post by Veronika Huber Climate skeptics sometimes like to claim that although global warming will lead to more deaths from heat, it will overall save lives due to fewer deaths from cold. But is this true? Epidemiological studies suggest the opposite. Mortality statistics generally show a distinct seasonality. More people die in the colder winter months than in the warmer summer months. In European countries, for example, the difference between the average number of …

Source: Will climate change bring benefits from reduced cold-related mortality? Insights from the latest epidemiological research