A water runoff deflector for use at a loading dock includes a seal suspended from a wall-mounted frame. A truck can back underneath the deflector so that the seal rests atop the truck's roof. The seal helps prevent water (snow, rain, ice, slush, etc.) on the truck's roof from flowing off the back end of the truck and spilling into the building. The seal helps block any water flowing along the truck's roof toward the doorway of the dock and redirects the flow off to either side of the truck. The deflector can be used in conjunction with or without a conventional dock seal or dock shelter. Unique front and rear bumper designs along with a pivotally yieldable frame make the runoff deflector particularly useful in adapting to trucks of various heights. In some cases, the front bumper includes multiple panels of different rigidity to ensure smooth truck departures.