Methods in a driver assistance system of a vehicle for detecting wetness on a road surface as well as a corresponding driver assistance system having a rearview camera are described. The method may include the following: recording an image of an area located behind the rear end of the vehicle, using the rearview camera; evaluating the recorded image for the presence of a spray trail caused by the vehicle; and selectively outputting, based on the evaluation, a wetness signal for triggering an automatic response by the driver assistance system to the wet road surface.