To provide an information terminal with which the user can easily know local weather information at a specific date and time, a system and method for weather forecast information service, and an on-vehicle navigation system with which the user can adjusts its running plan based on the local weather information.

When the user inputs a date and time and the information on a location for which the user wants to know weather forecast, namely, a destination from a portable telephone 50-1 by operating keys, the weather forecast information for the local area specified by the destination is transmitted from a server 20 to the telephone 50-1 through a communication network 3 and a base station 40, and the telephone 50-1 displays the transmitted contents in the form of a picture (weather map, etc.), characters, voice output, or their combinations. The on-vehicle navigation system displays the spots passed or transited by its own vehicle during running and the weather information for the destination so that the user may adjust its running plan.