Sunday 8 March 2015 2am local time
until Sunday 1 November 2015 2am local time
see: daylight saving time for details
USA and Canada Standard Time Date schedules here
Atlantic Time is the Atlantic Time Zone of Canada. Atlantic Standard Time (AST) is 4 hours behind Greenwich Mean Time (GMT-4).
In most provinces in Canada, Daylight-Saving Time (DST) is observed. During DST the time is shifted forward by 1 hour to ADT; which is 3 hours behind Greenwich Mean Time (GMT-3).
After the Summer months Atlantic Time is shifted back by 1 hour to Atlantic Standard Time (AST) or (GMT-4).