A method for medium-long term meteorological forecast starting from meteorological parameters of a large-scale geographical area having a predefined extent. The method: decomposes the meteorological parameters of the large-scale geographical area into a base component and a part arising as a variation on a regional scale, wherein the variation on a regional scale is defined as the difference between the large-scale geographical area and the base area; determines the temperature close to a surface of a base area, starting from the parameters available on the large-scale geographical area, using an empirical-statistical model; determines deviation in the meteorological parameters on a regional scale, starting from the parameters available on the large-scale geographical area, using a dynamic numerical model; effects combination, through an applicative model, of the empirical-statistical model and the dynamic numerical model to obtain the medium and long-term temperature forecast.