Examples of dynamic online energy forecasting are provided herein. An energy forecast request is received. An initial energy forecast is calculated in response to the request. One or more of a plurality of energy forecast model instances are selected as candidate forecast model instances. At least one of the candidate instances are transformed into an improved forecast model instance having greater accuracy than the candidate forecast model instance. The transformation is accomplished by determining alternative values for at least some parameters of an energy forecast model of the candidate forecast model instance. An improved energy forecast having a greater accuracy than the initial forecast can then be calculated using the improved forecast model instance.