Hurricane Sandy was relatively unusual. For example, its wind field was almost three times that of Katrina.
Sandy's path also included a rare "westward hook," rather than a more traditional eastward track.
Cause of the Westward Hook: Hurricane Sandy was steered between the blocking high pressure in Northern Canada and the low pressure trough over the Southeast U.S.
Source: Bostinno.com, NOAA, AGU Blogosphere, National Weather Service, Slate.com