Weather can have a profound effect on energy consumption, especially extremes of hot and cold temperatures. These variations in particular drive residential and commercial energy demand because space heating and cooling is such an important component. Traditional approaches are customized to the specific geography of interest. Energy regulators use a measure of divergence from normal temperatures to estimate peaks in demand when planning future capacity, or to strip out short-term weather effects to identify underlying growth trends. Energy traders marry weather forecasts to demand data to identify potential price peaks and troughs. What unites these analyses is that they tend to be either local or short term in nature; or both. However, the customization of methodology to a particular geography renders comparisons of the effects of weather between countries invalid.