Abstract: A vision system of a vehicle includes a camera and a control. The camera is disposed in the vehicle and has a field of view encompassing a portion of a windshield of the vehicle. The control includes an image processor operable to process image data captured by the camera. The control, responsive to processing of captured image data by the image processor, is operable to determine a driver's head and eyes and gaze direction via reflection at the windshield of the vehicle. The vision system may include an illumination source that emits illumination towards the windshield to enhance determination of the driver's head and eyes and gaze direction. The control, responsive to processing of captured image data by the image processor, may be operable to determine precipitation at the windshield.