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Atlantic Daylight Time (ADT)

Also known as: Atlantic Time (AT) and Atlantic Standard Time (AST)

Time zone map of ADT
Currently observing ADT.
Areas with same time currently (UTC -3).
Currently observing ADT – Atlantic Daylight Time.
Currently has same time zone offset as ADT (UTC -3) but different time zone name.

Atlantic Daylight Time (ADT) is 3 hours behind Coordinated Universal Time (UTC). This time zone is a Daylight Saving Time time zone and is used in: North America, Atlantic.

See full time zone map

What Is Atlantic Daylight Time?

Atlantic Daylight Time (ADT) is an eastern time zone in North America. It is used in the northeast of Canada.

It covers all or parts of four provinces in Canada but is not used in mainland United States or its US territories.

In North America, Atlantic Daylight Time shares a border with Eastern Daylight Time (EDT) in the west.


Atlantic Daylight Time (ADT) is a North American time zone in use from the second Sunday in March to the first Sunday in November during Daylight Saving Time (DST). Atlantic Standard Time (AST) is used during the remainder of the year.

ADT Is the Atlantic Time Zone

In everyday usage, ADT is often referred to as Atlantic Time (AT) or the Atlantic Time Zone. This can add a bit of confusion as the term Atlantic Time does not differentiate between standard time and Daylight Saving Time, so Atlantic Time switches between AST and ADT in areas that use DST during part of the year.

Most North American time zones have generic terms, including Pacific Time (PT), Mountain Time (MT), Central Time (CT), and Eastern Time (ET).

Converting Atlantic Daylight Time to Other US Time Zones

Where and When is ADT Observed?

North America

Canadian provinces using ADT in the summer and AST in the winter:

Areas of Greenland using ADT in the summer and AST in the winter:


Atlantic islands/territories using ADT in the summer and AST in the winter:

Other Time Zones in UTC -3

Some time zones exist that have the same offset as ADT, but can be found under a different name: