A vehicular vision system includes a camera and a processor operable to process captured image data. With the vehicle moving, the processor models outputs of photosensing elements of the camera as Gaussian distributions. With the vehicle moving, the processor determines an output of respective photosensing elements over multiple frames of captured image data, and determines whether the output of a photosensing element fits the Gaussian distribution for that element. Responsive to determination that the output of the element fits within the respective Gaussian distribution for that element, the system classifies that element as a blocked element. Responsive to determination that the output of the element does not fit within the respective Gaussian distribution for that element, the system classifies that element as a not blocked element. Responsive to determination that the ratio of blocked elements to not blocked elements is greater than a threshold ratio, a blockage condition is determined.