Patent ID: 8180502

Claim:
A navigation apparatus comprising: a travel route determination unit for determining a travel route of a vehicle; a detection area defining unit for defining a detection area, wherein the detection area is defined as an area that is within a predetermined range from the travel route determined by the travel route determination unit, and wherein whether or not noteworthy weather phenomenon in the detection area affects the vehicle is detected; a weather information obtaining unit for obtaining weather information that is set to a first sectional unit on a map; and a determination unit for deciding whether or not an affecting area is at least partially existing in the detection area defined by the detection area defining unit with reference to the weather information, wherein the affecting area is made up of the first sectional unit to which the noteworthy weather phenomenon is set, and wherein the determination unit determines that the weather phenomenon corresponding to the affecting area is affecting when the affecting area is at least partially existing in the detection area, wherein the detection area defining unit uses the detection area from a second sectional unit on the map, the detection area defining unit defines the second sectional unit for composing the detection area as a smaller area than the first sectional unit for composing the affecting area.