Touristic destinations and thus mountain touristic destinations face serious seasonality challenges. The most often seasonal peaks are in the winter season (Kopaonik and Stara Planina) or during the summer season (Zlatibor) and fall during the rest of the season. The subject of the paper places particular emphasis on forecasting seasonality and methods to measure it by applying different statistical and economic techniques. Some of the causes and consequences of seasonal trends within the tourism development of the three leading mountain centers of Serbia in terms of the development of mountain, sports, and recreational tourism are also reviewed.