Atlantic Time Zone

Last updated
Atlantic Time Zone
Time zone
  Atlantic Time Zone
UTC offset
AST UTC−04:00
ADT UTC−03:00
Current time
06:48, 18 March 2024 AST [refresh]
07:48, 18 March 2024 ADT [refresh]
Observance of DST
DST is observed in parts of this time zone.

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 and some Caribbean islands. During part of the year, some portions of the zone observe daylight saving time, 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 of the 60th meridian west of the Greenwich Observatory.


In Canada, the provinces of New Brunswick, [1] Nova Scotia, [2] and Prince Edward Island 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 (eastern Côte-Nord and the Magdalen Islands) also observe Atlantic Time. Officially, the entirety of Newfoundland and Labrador observes Newfoundland Standard Time, [3] but in practice Atlantic Time is used in most of Labrador.

No part of the continental United States uses Atlantic Time, although it is used by the territories of Puerto Rico and the U.S. Virgin Islands. 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 and the United States Congress before taking effect.

The United States National Hurricane Center'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. [4]

Areas covered


As of 2023, Bermuda is the only Caribbean territory to observe DST.

North America

Additional local areas

U.S. states considering a change to Atlantic Standard Time

All six of the New England 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 lies east of that meridian. A Massachusetts 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. [5] In May 2017, the Maine Senate approved a change to AST, on the condition that there would be a referendum, and that Massachusetts and New Hampshire decided to make the same switch. [6] Also in 2017, the New Hampshire House of Representatives approved a bill in favor of a regional change, but this was voted down by the state's Senate. [7] Similar bills have been put forward in Connecticut, Rhode Island, and Vermont. [6] [8]

In 2018, Florida 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 / Eastern Standard Time. [9] [10] However, the change cannot take effect until it is passed into federal law by the United States Congress. [10]

On March 15, 2022, the United States Senate 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; [11] the bill was not brought to a vote in the House. [12] A similar bill was introduced in the Senate in 2023. [13]

See also

Related Research Articles

<span class="mw-page-title-main">Central Time Zone</span> Time zone in North America

The North American Central Time Zone (CT) is a time zone in parts of Canada, the United States, Mexico, Central America and some Caribbean islands.

<span class="mw-page-title-main">Eastern Time Zone</span> North American time zone (UTC−5 and UTC−4)

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.

<span class="mw-page-title-main">Mountain Time Zone</span> Time zone of North America

The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC) when standard time (UTC−07:00) is in effect, and by subtracting six hours during daylight saving time (UTC−06:00). The clock time in this zone is based on the mean solar time at the 105th meridian west of the Greenwich Observatory. In the United States, the exact specification for the location of time zones and the dividing lines between zones is set forth in the Code of Federal Regulations at 49 CFR 71.

<span class="mw-page-title-main">Pacific Time Zone</span> North American time zone

The Pacific Time Zone (PT) is a time zone encompassing parts of western Canada, the western United States, and western Mexico. Places in this zone observe standard time by subtracting eight hours from Coordinated Universal Time (UTC−08:00). During daylight saving time, a time offset of UTC−07:00 is used.

<span class="mw-page-title-main">Alaska Time Zone</span> Time zone in Alaska

The Alaska Time Zone observes standard time by subtracting nine hours from Coordinated Universal Time (UTC−09:00). During daylight saving time its time offset is eight hours (UTC−08:00). The clock time in this zone is based on mean solar time at the 135th meridian west of the Greenwich Observatory.

<span class="mw-page-title-main">Time in the United States</span> U.S. time zones

In the United States, time is divided into nine standard time zones covering the states, territories and other US possessions, with most of the country observing daylight saving time (DST) for approximately the spring, summer, and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation, but no single map of those existed until the agency announced intentions to make one in September 2022. Official and highly precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and Technology (NIST) ; and the United States Naval Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations.

<span class="mw-page-title-main">Summer time in Europe</span> Variation of standard clock time

Summer time in Europe is the variation of standard clock time that is applied in most European countries in the period between spring and autumn, during which clocks are advanced by one hour from the time observed in the rest of the year, with a view to making the most efficient use of seasonal daylight. It corresponds to the notion and practice of daylight saving time (DST) to be found in some other parts of the world.

Time in New Zealand is divided by law into two standard time zones. The main islands use New Zealand Standard Time (NZST), 12 hours in advance of Coordinated Universal Time (UTC) / military M (Mike), while the outlying Chatham Islands use Chatham Standard Time (CHAST), 12 hours 45 minutes in advance of UTC / military M^ (Mike-Three).

<span class="mw-page-title-main">Newfoundland Time Zone</span> Time zone in Newfoundland and Labrador, Canada

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 time in this zone is based on the mean solar time of the meridian 52 degrees and 30 arcminutes west of the Greenwich Observatory. It is observed solely in the Canadian province of Newfoundland and Labrador. The Newfoundland Time Zone is the only active time zone with a half-hour offset from UTC in the Americas.

<span class="mw-page-title-main">UTC−04:00</span> Identifier for a time offset from UTC of −4

UTC−04:00 is an identifier for a time offset from UTC of −04:00.

<span class="mw-page-title-main">Time in Australia</span> Time zones in Australia

Australia uses three main time zones: Australian Eastern Standard Time, Australian Central Standard Time and Australian Western Standard Time.

<span class="mw-page-title-main">Time in Canada</span> Time zones of Canada

Canada is divided into six time zones. Most areas of the country's provinces and territories operate on standard time from the first Sunday in November to the second Sunday in March and daylight saving time the rest of the year.

<span class="mw-page-title-main">Daylight saving time in the United States</span> Practice of setting the clock forward by one hour in the United states

Most of the United States observes daylight saving time, the practice of setting the clock forward by one hour when there is longer daylight during the day, so that evenings have more daylight and mornings have less. Exceptions include Arizona, Hawaii, and the territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands. The Uniform Time Act of 1966 established the system of uniform daylight saving time throughout the US.

In Canada, daylight saving time (DST) is observed in nine of the country's ten provinces and two of its three territories—though with exceptions in parts of several provinces and Nunavut.

Daylight saving time in the Americas is the arrangement in the Americas by which clocks are advanced by one hour in spring and moved back in autumn, to make the most of seasonal daylight. The practice is widespread in North America, with most of Canada and the United States participating, but much less so in Central and South America.

<span class="mw-page-title-main">Daylight saving time by country</span>

Daylight saving time (DST), also known as summer time, is the practice of advancing clocks during part of the year, typically by one hour around spring and summer, so that daylight ends at a later time of the day. As of 2024, DST is observed in most of Europe, most of North America and parts of Africa and Asia around the Northern Hemisphere summer, and in parts of South America and Oceania around the Southern Hemisphere summer. It was also formerly observed in other areas.

<span class="mw-page-title-main">Time in Florida</span> Time zone of Florida, United States

Most of Florida is in the Eastern Time Zone.

<span class="mw-page-title-main">Sunshine Protection Act</span> Proposed U.S. federal law to make daylight saving time permanent

The Sunshine Protection Act is a proposed United States federal law that would make U.S. daylight saving time permanent, meaning the time would no longer change twice per year. The bill has been proposed during several sessions of Congress. In 2022, the Senate passed the bill by unanimous consent, although several senators stated later that they would have objected if they had known that the bill could pass. No iteration of the bill has passed the House.

<span class="mw-page-title-main">Permanent time observation in the United States</span> Year-round standard time in the US

Establishing either permanent standard or daylight saving time (DST) eliminates the practice of semi-annual clock changes, specifically the advancement of clocks by one hour from standard time to DST on the second Sunday in March and the retraction of clocks by one hour from DST to standard time on the first Sunday in November.

Time in the Kingdom of the Netherlands is denoted by Central European Time during the winter as standard time in the Netherlands, which is one hour ahead of coordinated universal time (UTC+01:00), and Central European Summer Time (CEST) during the summer as daylight saving time, which is two hours ahead of coordinated universal time (UTC+02:00). The Caribbean Netherlands – which consist of the islands of Bonaire, Sint Eustatius and Saba – all observe Atlantic Standard Time (AST) year-round, which is four hours behind coordinated universal time (UTC−04:00).


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  2. "Time Definition Act". Archived from the original on 5 June 2008. Retrieved 2008-06-02.
  3. "RSNL1990 CHAPTER S-23 – STANDARD TIME ACT" . Retrieved 2007-11-16.
  4. "Advisories". National Hurricane Center.
  5. "Commission: Massachusetts Should Change Time Zones, But Not On Its Own". November 1, 2017. Retrieved March 15, 2018.
  6. 1 2 "Maine Considers Atlantic Standard Time". Retrieved March 15, 2018.
  7. "Senate votes down push to switch N.H.'s time zone". May 11, 2017. Retrieved March 15, 2018.
  8. Haigh, Susan (2019-01-15). "Connecticut bill is latest calling for time zone change". Providence Journal. Retrieved 2019-09-10. In Vermont, Democrat Rep. Samuel Young this year has submitted legislation that would establish year-round Eastern daylight saving time.
  9. "Should Florida keep Daylight Saving Time all year? It could happen". miamiherald. Retrieved 2019-03-12.
  10. 1 2 Lemongello, Steven. "Florida's year-round daylight saving time law on hold in Congress". Retrieved 2019-03-12.
  11. Palya, Ashley (2022-03-15). "Turning Back Clocks A Thing Of The Past? Senate Passes Sunshine Protection Act". International Business Times. Retrieved 2022-03-17.
  12. Schnell, Mychael (July 25, 2022). "Permanent daylight saving time hits brick wall in House". The Hill.
  13. Bink, Addy (March 2, 2023). "Daylight saving time: New bill could stop the clocks from changing". The Hill.