|Atlantic Time Zone
|Observance of DST
|DST is observed in certain regions of this time zone between the 2nd Sunday in March and the 1st Sunday in November.
||10 Mar 2013
||3 Nov 2013
The Atlantic Time Zone (AST) is a geographical region that keeps standard time by subtracting four hours from Coordinated Universal Time (UTC), resulting in UTC-4; during some part of the year it observes daylight saving time by subtracting three hours (UTC-3). The clock time in this zone is based on the mean solar time of the 60th meridian west of the Greenwich Observatory.
In Canada, the provinces of New Brunswick and Nova Scotia reckon time specifically as an offset of 4 hours from Greenwich Mean time (GMT-4). Prince Edward Island and small portions of Quebec (eastern Côte-Nord and the Magdalen Islands) are also part of the Atlantic Standard Time Zone. Officially, the entirety of Newfoundland and Labrador observes Newfoundland Standard Time, but in practice most of Labrador uses the Atlantic Standard Time Zone.
No portion of the continental United States is located in the Atlantic Standard Time Zone, however the territories of Puerto Rico and the U.S. Virgin Islands do fall under Atlantic Standard Time.
Those portions of the Atlantic Standard Time Zone that participate in daylight saving time do so as Atlantic Daylight Time (ADT), which has one hour added to make it only three hours behind GMT (UTC-3).
Cities and capitals 
- Bridgetown, Barbados, [No DST]
- Hamilton, Bermuda
- Cape Breton Regional Municipality, Nova Scotia, Canada
- Charlottetown, Prince Edward Island, Canada
- Fredericton, New Brunswick, Canada
- Halifax Regional Municipality, Nova Scotia, Canada
- Moncton, New Brunswick, Canada
- Port of Spain, Trinidad and Tobago [No DST]
- Saint John, New Brunswick, Canada
- Summerside, Prince Edward Island, Canada
- Santo Domingo, Dominican Republic [No DST]
- San Juan, Puerto Rico [No DST]
External links