Abstract: A sensor module includes a housing. A heat source is located within the housing of the sensor module and a plurality of temperature sensors are mounted in housing of said sensor module. At least one temperature sensors is located adjacent to the heat source and at least one other temperature sensor is spaced from the heat source. A humidity sensor is located within the housing of the sensor module. A controller is connected to the plurality of temperature sensors and to the humidity sensor for determining at least one of relative humidity and temperature at the windscreen using a regression analysis and for providing a control signal indicative thereof.