An especially simple and economical moisture sensor with temperature compensation is provided. To this end, in addition to a measuring capacitor, a second capacitor is arranged on a window of a motor vehicle, wherein the second capacitor is not affected by the moisture and/or water droplets. For analysis, a differential measurement of the capacitances of the measuring capacitor and of the second capacitor is carried out, from which is determined a degree of wetting of the window not influenced by the window temperature.