North American time zones:

Time zone offset: UTC - 4 hours

AST is 4 hours behind of Coordinated Universal Time (UTC)

Note that during summer daylight saving time/summer time is observed, and ADT is used instead.

Time zone abbreviations: AST, HNA

Full name is Atlantic Standard Time
HNA – Heure Normale de l'Atlantique (French)

Email time zone indicator: -0400

An email sent from someone in the 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 AST, as other time zones could have the same UTC offset).

Where and when is AST observed?

AST is used during winter in these Canadian provinces (ADT during summer)

• Most of the mainland (Labrador) part of the province of Newfoundland and Labrador

• New Brunswick

• Nova Scotia

• Prince Edward Island

AST is used all year in these regions

• Quebec - East of 63 West only.

Example location in AST

• Halifax - during winter

Other time zones in North America

• NST - Newfoundland Standard Time

• NDT - Newfoundland Daylight Time

• ADT - Atlantic Daylight Time

• EST - Eastern Standard Time

• EDT - Eastern Daylight Time

• CST - Central Standard Time

• CDT - Central Daylight Time

• MST - Mountain Standard Time

• MDT - Mountain Daylight Time

• PST - Pacific Standard Time

• PDT - Pacific Daylight Time

• AKST - Alaska Standard Time

• AKDT - Alaska Daylight Time

• HAST - Hawaii-Aleutian Standard Time

• HADT - Hawaii-Aleutian Daylight Time