Snowplows may be out-driving on stormless days for a number of reasons. First, every driver undergoes pre-season training, and they work on practicing their routes and sharpening their skills on days without snow. Second, plows may be scanning streets that need secondary clearing or snow that must be hauled away. Finally, plows may be out sanding streets. If you see a plow out with its blades up on a day without snow, it is likely spreading sand.