As a surfer, I primarily surf breaks in NJ and Virginia Beach. I know they are out there.
Many myths regarding the aversion of Great Whites to warm water are suspected to be tied to the availability of food. With the rise of the seal population in Hawaii, researchers have found more great whites. It may have been that while many such prey items as the monk seal had been slaughtered to numbers that wouldn't sustain adequate hunting, the sharks weren't lingering in Hawaii long enough to be as apparent. Plus, the numbers of the Great White population may be lower than scientists believed. It's also suspected that sharks (even warm water sharks) may use deeper, colder water to cool off while hunting. I just watched a documentary on Discovery on demand about that, but because it was Discovery, I don't know it that fact about temperature regulation is science or just a theory without any supporting data.
Whatever the reason, many species of sharks will prefer to hunt in areas in which drop off's allow them to return to deeper waters and stalk the shallows, sometimes, repeating the process of cruising between deep water and shallow water over the course of a single night.
