The Atlantic Time Zone is a geographical region that keeps standard time—called Atlantic Standard Time (AST)—by subtracting four hours from Coordinated Universal Time (
UTC), resulting in
UTC−04:00. AST is observed in parts of North America including several Caribbean islands. During part of the year, some portions of the zone observe
daylight saving time
Daylight saving time (DST), also referred to as daylight savings time, daylight time (Daylight saving time in the United States, United States and Daylight saving time in Canada, Canada), or summer time (British Summer Time, United Kingdom, ...
, referred to as Atlantic Daylight Time (ADT), by moving their clocks forward one hour to
UTC−03:00. The clock time in this zone is based on the
mean solar time
Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day, based on the synodic rotation period. Traditionally, there are three types of time reckoning based ...
of the
60th meridian west of the
Greenwich Observatory.
In Canada, the provinces of
New Brunswick
New Brunswick is a Provinces and Territories of Canada, province of Canada, bordering Quebec to the north, Nova Scotia to the east, the Gulf of Saint Lawrence to the northeast, the Bay of Fundy to the southeast, and the U.S. state of Maine to ...
,
Nova Scotia
Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
, and
Prince Edward Island
Prince Edward Island is an island Provinces and territories of Canada, province of Canada. While it is the smallest province by land area and population, it is the most densely populated. The island has several nicknames: "Garden of the Gulf", ...
are in this zone, though legally they calculate time specifically as an offset of four hours from Greenwich Mean Time (GMT–4) rather than from UTC. Small portions of
Quebec
Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
(eastern
Côte-Nord
Côte-Nord (Region 09) (, ; ) is an List of regions of Quebec, administrative region of Quebec, on the Quebec-Labrador peninsula, Quebec-Labrador Peninsula, Canada.
The region runs along the St. Lawrence River and then the Gulf of St. Lawrence, ...
and the
Magdalen Islands) also observe Atlantic Time. Officially, the entirety of
Newfoundland and Labrador
Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the populatio ...
observes
Newfoundland Standard Time
The Newfoundland Time Zone (NT) is a geographic region that keeps time by subtracting 3.5 hours from Coordinated Universal Time ( UTC) during standard time, resulting in UTC−03:30; or subtracting 2.5 hours during daylight saving time. The clock ...
, but in practice Atlantic Time is used in most of
Labrador
Labrador () is a geographic and cultural region within the Canadian province of Newfoundland and Labrador. It is the primarily continental portion of the province and constitutes 71% of the province's area but is home to only 6% of its populatio ...
.
No part of the
continental United States uses Atlantic Time, although it is used by the territories of
Puerto Rico
; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...
and the
U.S. Virgin Islands
The United States Virgin Islands, officially the Virgin Islands of the United States, are a group of Caribbean islands and a territory of the United States. The islands are geographically part of the Virgin Islands archipelago and are located ...
. In the 2010s, several U.S. states considered legislation to move from the Eastern Time Zone to Atlantic Standard Time. Any changes must be approved by the
United States Department of Transportation
The United States Department of Transportation (USDOT or DOT) is one of the executive departments of the U.S. federal government. It is headed by the secretary of transportation, who reports directly to the president of the United States a ...
and the
United States Congress
The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, ...
before taking effect.
The United States
National Hurricane Center
The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the IERS Reference Meridian, Prime Meridian and the 140th meridian ...
's official advisories typically report AST and UTC when tracking storms in the Caribbean that threaten the U.S., which may confuse the mainland public not familiar with the time zone designation (although AST is equivalent to
Eastern Daylight Time
The Eastern Time Zone (ET) is a time zone encompassing part or all of 23 states in the eastern part of the United States, parts of eastern Canada, and the state of Quintana Roo in Mexico.
* Eastern Standard Time (EST) is five hours behin ...
(EDT) for most of the Atlantic hurricane season).
Areas covered
Caribbean
*Antigua and Barbuda
*Barbados
*Dominica
*Dominican Republic
*France and
French overseas collectivities, in the following areas:
**
Guadeloupe
Guadeloupe is an Overseas departments and regions of France, overseas department and region of France in the Caribbean. It consists of six inhabited islands—Basse-Terre Island, Basse-Terre, Grande-Terre, Guadeloupe, Grande-Terre, Marie-Galant ...
**
Martinique
Martinique ( ; or ; Kalinago language, Kalinago: or ) is an island in the Lesser Antilles of the West Indies, in the eastern Caribbean Sea. It was previously known as Iguanacaera which translates to iguana island in Carib language, Kariʼn ...
**
Saint Barthélemy
Saint Barthélemy, officially the Collectivité territoriale de Saint-Barthélemy, also known as St. Barts (English) or St. Barth (French), is an overseas collectivity of France in the Caribbean. The island lies about southeast of the island ...
**
Saint-Martin
*Grenada
*Netherlands and
Dutch special municipalities, in the following areas:
**
Aruba
Aruba, officially the Country of Aruba, is a constituent island country within the Kingdom of the Netherlands, in the southern Caribbean Sea north of the Venezuelan peninsula of Paraguaná Peninsula, Paraguaná and northwest of Curaçao. In 19 ...
**
Bonaire
Bonaire is a Caribbean island in the Leeward Antilles, and is a Caribbean Netherlands, special municipality (officially Public body (Netherlands), "public body") of the Netherlands. Its capital is the port of Kralendijk, on the west (Windward an ...
**
Curaçao
Curaçao, officially the Country of Curaçao, is a constituent island country within the Kingdom of the Netherlands, located in the southern Caribbean Sea (specifically the Dutch Caribbean region), about north of Venezuela.
Curaçao includ ...
**
Saba
**
Sint Eustatius
Sint Eustatius, known locally as Statia, is an island in the Caribbean. It is a Caribbean Netherlands, special municipality (officially "Public body (Netherlands), public body") of the Netherlands.
The island is in the northern Leeward Islands ...
**
Sint Maarten
Sint Maarten () is a Countries of the Kingdom of the Netherlands, constituent country of the Kingdom of the Netherlands located in the Caribbean region of North America. With a population of 58,477 as of June 2023 on an area of , it encompasses ...
*Saint Kitts and Nevis
*Saint Lucia
*Saint Vincent and the Grenadines
*Trinidad and Tobago
*United Kingdom (
British Overseas Territories
The British Overseas Territories (BOTs) or alternatively referred to as the United Kingdom Overseas Territories (UKOTs) are the fourteen dependent territory, territories with a constitutional and historical link with the United Kingdom that, ...
), in the following areas:
**
Anguilla
Anguilla is a British Overseas Territories, British Overseas Territory in the Caribbean. It is one of the most northerly of the Leeward Islands in the Lesser Antilles, lying east of Puerto Rico and the Virgin Islands and directly north of Sa ...
**
British Virgin Islands
The British Virgin Islands (BVI), officially the Virgin Islands, are a British Overseas Territories, British Overseas Territory in the Caribbean, to the east of Puerto Rico and the United States Virgin Islands, US Virgin Islands and north-west ...
**
Montserrat
Montserrat ( , ) is a British Overseas Territories, British Overseas Territory in the Caribbean. It is part of the Leeward Islands, the northern portion of the Lesser Antilles chain of the West Indies. Montserrat is about long and wide, wit ...
*United States
territories, in the following areas:
**
Puerto Rico
; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...
**
United States Virgin Islands
The United States Virgin Islands, officially the Virgin Islands of the United States, are a group of Caribbean islands and a territory of the United States. The islands are geographically part of the Virgin Islands archipelago and are located ...
North America
*Canada, in the following areas:
**
Nova Scotia
Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
**
New Brunswick
New Brunswick is a Provinces and Territories of Canada, province of Canada, bordering Quebec to the north, Nova Scotia to the east, the Gulf of Saint Lawrence to the northeast, the Bay of Fundy to the southeast, and the U.S. state of Maine to ...
**
Prince Edward Island
Prince Edward Island is an island Provinces and territories of Canada, province of Canada. While it is the smallest province by land area and population, it is the most densely populated. The island has several nicknames: "Garden of the Gulf", ...
**Most of
Labrador
Labrador () is a geographic and cultural region within the Canadian province of Newfoundland and Labrador. It is the primarily continental portion of the province and constitutes 71% of the province's area but is home to only 6% of its populatio ...
**
Magdalen Islands, Quebec
**
Côte-Nord
Côte-Nord (Region 09) (, ; ) is an List of regions of Quebec, administrative region of Quebec, on the Quebec-Labrador peninsula, Quebec-Labrador Peninsula, Canada.
The region runs along the St. Lawrence River and then the Gulf of St. Lawrence, ...
(east of the
63rd meridian), Quebec (no DST)
Additional local areas
*Bermuda
*
Greenland
Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...
, in the following area:
**
Pituffik Space Base
Pituffik Space Base ( ; ; ), formerly Thule Air Base (), is a United States Space Force base located on the northwest coast of Greenland in the Kingdom of Denmark under a defense agreement between Denmark and the United States. 150 United Stat ...
U.S. states considering a change to Atlantic Standard Time
All six of the
New England
New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...
states in the northeastern U.S., currently in the Eastern Time Zone (with daylight saving time), have considered legislation to shift to UTC−04:00, equivalent to Atlantic Standard Time (with no observance of daylight saving time) or Eastern Daylight Time. Virtually all of this region is west of the theoretical western border of the zone at 67.5°W; only a small part of
Maine
Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...
lies east of that meridian. A
Massachusetts
Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...
commission concluded in 2017 that the benefits of changing to Atlantic Standard Time year-round would outweigh the disadvantages, provided that a majority of northeastern states make the same change. In May 2017, the
Maine Senate
The Maine Senate is the upper house of the Maine Legislature, the state legislature (United States), state legislature of the U.S. state of Maine. The Senate currently consists of 35 members representing an equal number of districts across the st ...
approved a change to AST, on the condition that there would be a referendum, and that Massachusetts and
New Hampshire
New Hampshire ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...
decided to make the same switch.
Also in 2017, the
New Hampshire House of Representatives
The New Hampshire House of Representatives is the lower house in the New Hampshire General Court, the bicameral State legislature (United States), legislature of the state of New Hampshire. The House of Representatives consists of 400 members com ...
approved a bill in favor of a regional change, but this was voted down by the
state's Senate. Similar bills have been put forward in
Connecticut
Connecticut ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Rhode Island to the east, Massachusetts to the north, New York (state), New York to the west, and Long Island Sound to the south. ...
,
Rhode Island
Rhode Island ( ) is a state in the New England region of the Northeastern United States. It borders Connecticut to its west; Massachusetts to its north and east; and the Atlantic Ocean to its south via Rhode Island Sound and Block Is ...
, and
Vermont
Vermont () is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York (state), New York to the west, and the Provinces and territories of Ca ...
.
In 2018,
Florida
Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
enacted into law the "Sunshine Protection Act", under which the state would observe daylight saving time year-round. Most of the state would permanently keep Eastern Daylight Time, which is equivalent to Atlantic Standard Time; the state's
panhandle region would move to year-round
Central Daylight Time
The North American Central Time Zone (CT) is a time zone in parts of Canada, the United States, Mexico, Central America, and a few Caribbean islands.
In parts of that zone (20 states in the US, three provinces or territories in Canada, and ...
.
However, the change cannot take effect until it is passed into federal law by the
United States Congress
The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, ...
.
On March 15, 2022, the
United States Senate
The United States Senate is a chamber of the Bicameralism, bicameral United States Congress; it is the upper house, with the United States House of Representatives, U.S. House of Representatives being the lower house. Together, the Senate and ...
voted unanimously to advance a federal version of the "Sunshine Protection" legislation from Florida, also called the "Sunshine Protection Act", to the
United States House of Representatives
The United States House of Representatives is a chamber of the Bicameralism, bicameral United States Congress; it is the lower house, with the U.S. Senate being the upper house. Together, the House and Senate have the authority under Artic ...
; the bill was not brought to a vote in the House. A similar bill was introduced in the Senate in 2023.
See also
*
Daylight saving time in the Americas
References
External links
Atlantic Standard Time: ''current time (live clock)''Atlantic Daylight Time: ''current time (live clock)''Web clock (Official times across Canada)
{{authority control
Time zones
Time zones in the United States