Methods and systems for detecting weather conditions including sunlight using onboard vehicle sensors are described. In one example, a method is provided that includes receiving laser data collected for an environment of a vehicle. The method also includes associating laser data points with one or more objects in the environment, and determining given laser data points that are unassociated with the one or more objects in the environment as being representative of an untracked object at a given position with respect to the vehicle. The method also includes determining that the untracked object remains at a substantially same relative position with respect to the vehicle as the vehicle moves, and identifying by the computing device an indication that a weather condition of the environment of the vehicle is sunny.