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AST – Atlantic Standard Time / Atlantic Time (Standard Time)

Also known as: AT – Atlantic Time

Atlantic Standard Time Note:

Atlantic: AST is currently not observed because locations are on DST. Locations are currently observing ADT instead.

North America: Only some locations are currently on AST because most places in this time zone are currently on DST. Locations that are on AST part of the year are currently on ADT.

Time zone map of AST
Currently observing AST.
Observes AST part of the year.
Areas with same time currently (UTC -4:00).
Currently observing AST – Atlantic Standard Time.
Observes AST – Atlantic Standard Time part of the year, but not currently.
Currently has same time zone offset as AST (UTC -4:00) but different time zone name.

Atlantic Standard Time (AST) is 4 hours behind Coordinated Universal Time (UTC). This time zone is a standard time zone and is used in: North America, Atlantic, Caribbean.

This time zone is often called Atlantic Time Zone.

See full time zone map

Summer Time & DST

Some places observe daylight saving time/summer time during the summer, and therefore use ADT (Atlantic Daylight Time) in the summer.

Email time zone indicator: -0400

An email sent from someone in the Atlantic Standard Time (AST) time zone will have the time zone listed as "-0400" in the headers of the email. (However, "-0400" does not have to be in Atlantic Standard Time, as other time zones could have the same UTC offset).

Where and when is AST observed?

North America

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

  • Most of Labrador (mainland part of the province of Newfoundland and Labrador)
  • New Brunswick
  • Nova Scotia
  • Prince Edward Island

Canadian provinces using AST all year

  • Quebec - East of 63 West only.

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

  • Thule area


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

  • Bermuda


Caribbean countries/territories using AST all year

  • Anguilla
  • Antigua and Barbuda
  • Aruba
  • Barbados
  • Bonaire
  • British Virgin Islands
  • Curaçao
  • Dominica
  • Dominican Republic
  • France
  • Grenada
  • Guadeloupe
  • Martinique
  • Montserrat
  • Puerto Rico
  • Saint Kitts and Nevis
  • Saint Lucia
  • Saint Vincent and Grenadines
  • Sint Maarten
  • Trinidad and Tobago
  • US Virgin Islands

Other time zones in UTC -4:00

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

AST time now


Sunday, March 29, 2015

  • AST will be observed in Halifax, Hamilton starting from Nov 1, 2015 at 2:00 AM
  • UTC Offset: UTC -4:00
  • Same time as Washington DC

Find current time and time zone by city


Other names

AST – Tiempo Estándar del Atlántico (Spanish)
HNA – Heure Normale de l'Atlantique (French)

Other time zones named AST

AST – Arabia Standard Time

Example cities

Canada – Halifax (Winter)
Canada – Blanc-Sablon (All Year)
Bermuda – Hamilton (Winter)
Dominican Republic – Santo Domingo (All Year)
Netherlands – Philipsburg (All Year)

Related time zones

ADT – Atlantic Daylight Time (Daylight Time)

Time Zone Map with DST

Time zone map

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Time zones by continent/region

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