Forecasts refer to the complete and thorough estimations, guesses, or predictions that are made by the project team on the particular conditions in the projects future that may arise. These forecasts are derived through a careful and explicit evaluation of all information and knowledge that is available at the time that the aforementioned forecast is made. Forecasts can be updated and reissued based on changes to that information, and also as the project is executed and additional work performance information is made available. The in formation that is made available is typically derived from the past performance of the project as well as any anticipated future performances. This information includes information that may impact the project at some point in the future. Some examples of the type of information that must be weighed when making a complete forecast are examples such as the estimate at completion, or in other words, the estimate to complete. Forecasts are essential for trying to get a predictory big picture view of the project.’
This term is defined in the 3rd and the 4th edition of the PMBOK.