A controller for a vehicle executes a base temperature calculation process that calculates a base temperature of a component of the internal combustion engine, a correction value calculation process that calculates a correction value, a vehicle line reflection process when the vehicle including the component of which temperature is estimated is a temperature-estimated vehicle that is in a line of vehicles in order to reflect, on the correction value, a tendency of the component to be less cooled when the temperature-estimated vehicle is a trailing vehicle than when the temperature-estimated vehicle is a leading vehicle, a rearmost reflection process when the temperature-estimated vehicle is in the line of vehicles in order to reflect, on the correction value, a tendency of the component to be more cooled when the temperature-estimated vehicle is a rearmost vehicle, and a component temperature estimation process that corrects the base temperature with the correction value.