A powerful nor'easter is battering the East Coast this weekend, bringing major coastal flooding, damaging winds and heavy rain from the Carolinas to southern New England.

About 84,600 homes and businesses were without power across five Northeast states by midday Saturday, according to PowerOutage.us, with New Jersey, Connecticut and Long Island hit hardest. Wind gusts topped 60 mph on Long Island, Cape Cod and the islands, according to the National Weather Service, and more than 400 flights were canceled nationwide, most of them at Boston Logan.

Water rose more than 3 feet above th...