Shortly after peaking, the hurricane turned to the north and gradually weakened as wind shear from an upper-level trough to its northwest increased. By early on November 17, the low-cloud circulation became partially exposed on the west side of the deep convection, and it is estimated that Sergio weakened to a tropical storm later that day. A ridge to its north and northeast turned the storm to the northwest and later to the west as Sergio gradually weakened.
Shortly after reaching its peak, the hurricane shifted northward and gradually diminished as wind shear from an upper-level trough to its northwest intensified. By early on November 17, the low-cloud circulation partially emerged on the west side of the deep convection, and it is estimated that Sergio weakened to a tropical storm later that day. A ridge to its north and northeast steered the storm northwestward and then westward as Sergio gradually weakened.