AST/ADT Atlantic Time Zone

Standard time and daylight time is observed by this time zone; AST Atlantic Standard Time is 4 hours behind of UTC/GMT time and ADT Atlantic Daylight Time is behind by 3 hours.

Atlantic Daylight Time:
Sunday October 1st 12:16am ADT
Status: Time Zone: UTC/GMT Offset:
Being Observed
ADT -03:00
Atlantic Standard Time:
Saturday September 30th 11:16pm AST
Status: Time Zone: UTC/GMT Offset:
Not Being Observed AST -04:00
Year: ADT Begins: ADT Ends:
2025 Sunday March 9th Sunday November 2nd
2024 Sunday March 10th Sunday November 3rd
2023 Sunday March 12th Sunday November 5th
2022 Sunday March 13th Sunday November 6th
2021 Sunday March 14th Sunday November 7th

Countries which observe the AST/ADT time zone:


  • Canada*
  • Greenland*


  • Bermuda

(*) indicates that the time zone is only observed in certain areas of the country. No asterisk indicates that the entire country observes this time zone.

Areas in Canada which observe the Atlantic Time Zone

Majority of Labrador from Cartwright north and west observes AST during the winter and ADT during the summer and the south-eastern tip near Newfoundland observes the Newfoundland Time Zone. New Brunswick, Nova Scotia and Prince Edward Island observe only AST.

Areas in Greenland which observe the Atlantic Time Zone

  • Thule Air Base (IATA THU)
Atlantic Time Zone Identifiers:
(BM) Atlantic/Bermuda(CA) America/Glace_Bay
(CA) America/Goose_Bay(CA) America/Halifax
(CA) America/Moncton(GL) America/Thule
« List of World Time Zones