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Atlantic Daylight Time (ADT)

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ADT time now

21:20:05
Fri, 27 Jun 2025
UTC Offset: UTC -3

Atlantic Daylight Time (ADT) operates at UTC−3 and is the daylight saving time observed in regions that follow Atlantic Standard Time (AST, UTC−4) during the rest of the year. ADT is commonly used in Atlantic Canada, some Caribbean territories, and a small part of Greenland during the summer months, typically from March to November. It is often referred to simply as "Atlantic Daylight Time" and is one hour ahead of AST.

Importance and Global Use of ADT

ADT helps regions maximize daylight during summer by shifting the clock one hour ahead, supporting energy efficiency, extended evening activities, and improved alignment with daylight hours. This is particularly beneficial for communities in higher latitudes where daylight hours change significantly with the seasons.

Globally, ADT plays a role in maintaining consistent time zone coordination during the daylight saving period. It is important for transportation, broadcasting, finance, and digital communications in the Atlantic region. ADT ensures smooth seasonal time adjustments in areas that rely heavily on both local and international scheduling.

Where and When ADT is used worldwide

North America

Canadian provinces using ADT during summer and AST during winter

  • Most of mainland Labrador, in the province of Newfoundland and Labrador
  • Nova Scotia
  • New Brunswick
  • Prince Edward Island

Areas of Greenland using ADT during summer and AST during winter

  • Thule Air Base

Atlantic

Atlantic islands and territories using ADT during summer and AST during winter

  • Bermuda

Other Time Zones in UTC -3

Other time zones share the same offset as Atlantic Daylight Time (ADT), but are known by different names. While their clocks align, they may represent different regions or countries based on local time zone definitions.

  • Argentina Time – ART
  • Brasília Time – BRT
  • Chile Summer Time – CLST
  • Falkland Islands Summer Time – FKST
  • French Guiana Time – GFT
  • Pierre & Miquelon Standard Time – PMST
  • Paraguay Summer Time – PYST
  • Suriname Time – SRT
  • Uruguay Time – UYT