Abstract: A method for a navigation device to change a background weather pattern of an electronic map comprises steps of: reading a plurality of positioning signals received by a positioning module and calculating a current location of the navigation accordingly; reading from a map database and a real-time weather database, respectively, an electronic map and a background weather pattern that correspond to the current location, and outputting the electronic map and the background weather pattern corresponding to the current location on a display device; determining whether it is necessary to change the electronic map corresponding to the current location; and when it is necessary, reading from the real-time weather database a background weather pattern corresponding to an updated current location and replacing the presently displayed electronic map and background weather pattern with an electronic map and a background weather pattern corresponding to the updated current location.