A snow stop has a flat blade formed with curved upper and lower edges. Openings extend through the blade for weight reduction and for permitting passage of air and fluids. A slot extends upward from a center of a blade for receiving a standing seam of a metal roof, and a boss extends from the blade around the slot for fixing the blade on a roof seam. The boss has an outward extending support with a ledge, which continues outward from a top of the slot for resting on top of a standing seam. The boss extends downward and terminates downwardly in rounded lobes. Holes extend through the lobes parallel to the blade, and fasteners extend through the holes for engaging sides of a standing seam. The fasteners cooperate with the ledge to prevent movement of the snow stop on the seam.