Ice cream shop Matsumoto's Shave Ice. Haleiwa. O'ahu. Hawaii has its own time zone, "Hawaiian Standard Time". On the islands advance is not used in the summer time, while in the United States itself, which means that if you communicate with the west coast of the United States during that time will have to pass three hours when Hawaii , and if not, you only need to forward two hours. To the east coast of the United States the difference is five to six hours respectively.