Atlantic Standard Time ( AST ) = GMT-4
Atlantic Daylight Time ( ADT ) = GMT-3
Prince Edward Island is in the Atlantic Time Zone in Canada, which is 4 hours behind Greenwich Mean Time ( GMT-4 ).
Like most provinces in Canada, Daylight Saving Time is observed in Prince Edward Island, where the time is shifted forward by 1 hour, resulting in a 3 hours difference behind Greenwich Mean Time ( GMT-3 )
After the Summer months the time is shifted back by 1 hour resulting in the normal 4 hours difference behind GMT.