This is a list of time zones from release 2024b of the tz database. [2]
This is a list of time zones from release 2024b of the tz database. [2]
Standard Time (SDT) and Daylight Saving Time (DST) offsets from UTC in hours and minutes.
For zones in which Daylight Saving is not observed, the DST offset shown in this table is a simple duplication of the SDT offset.
The UTC offsets are based on the current or upcoming database rules. This table does not attempt to document any of the historical data which resides in the database.
In Ireland, what Irish law designates as "standard time" is observed during the summer, with clocks turned one hour ahead of UTC. [3] [4] The SDT column shows the offset from UTC during the winter, even in Ireland, where that's referred to as "winter time", and the DST column shows the offset from UTC during the summer, even in Ireland, where that's referred to as "standard time".
Time zone abbreviations for both Standard Time and Daylight Saving Time are shown exactly as they appear in the database. See strftime and its "%Z" field.
Some of zone records use 3 or 4 letter abbreviations that are tied to physical time zones, others use numeric UTC offsets.
In Ireland, what Irish law designates as "standard time" is observed during the summer, with clocks turned one hour ahead of UTC. [3] [4] The SDT column shows the abbreviation used during the winter, even in Ireland, and the DST column shows the abbreviation used during the summer, which is "IST", where the "S" in "IST" stands for "Standard", not "Summer".
| Region | Zones | Links | Total |
|---|---|---|---|
| Africa | 19 | 35 | 54 |
| America | 120 | 48 | 168 |
| Antarctica | 8 | 4 | 12 |
| Asia | 74 | 25 | 99 |
| Atlantic | 8 | 4 | 12 |
| Australia | 11 | 12 | 23 |
| Europe | 38 | 26 | 64 |
| Indian | 3 | 8 | 11 |
| Pacific | 30 | 14 | 44 |
| Etc | 28 | 7 | 35 |
| Other | 1 | 74 | 75 |
| Total | 340 | 257 | 597 |
| Source File | Zones | Links | Total |
|---|---|---|---|
| factory | 1 | 0 | 1 |
| africa | 20 | 0 | 20 |
| antarctica | 6 | 0 | 6 |
| asia | 58 | 0 | 58 |
| australasia | 39 | 0 | 39 |
| etcetera | 28 | 1 | 29 |
| europe | 65 | 0 | 65 |
| northamerica | 78 | 0 | 78 |
| southamerica | 45 | 0 | 45 |
| backward | 0 | 256 | 256 |
| Total | 340 | 257 | 597 |
A time zone is an area which observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.
Daylight saving time (DST), also referred to as daylight saving(s), daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to make better use of the longer daylight available during summer so that darkness falls at a later clock time. The typical implementation of DST is to set clocks forward by one hour in spring or late winter, and to set clocks back by one hour to standard time in the autumn (or fall in North American English, hence the mnemonic: "spring forward and fall back").
Western European Summer Time is a summer daylight saving time scheme, 1 hour ahead of Greenwich Mean Time and Coordinated Universal Time. It is used in:
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.
Israel Standard Time (IST) is the standard time zone in Israel. It is two hours ahead of UTC (UTC+02:00).
Australia uses three main time zones: Australian Eastern Standard Time, Australian Central Standard Time and Australian Western Standard Time.
There are 11 time zones in Russia, which currently observe times ranging from UTC+02:00 to UTC+12:00. Daylight saving time (DST) has not been used in Russia since 26 October 2014. From 27 March 2011 to 26 October 2014, permanent DST was used.
Argentina is located at a longitude that would naturally put it in the UTC−04:00 or UTC−05:00 time zone; however, it actually uses the UTC−03:00 time zone. Argentina determines whether to change clocks in observation of daylight saving time on a year-by-year basis, and individual provinces may opt out of the federal decision. At present, Argentina does not change clocks.
The tz database is a collaborative compilation of information about the world's time zones and rules for observing daylight saving time, primarily intended for use with computer programs and operating systems. Paul Eggert has been its editor and maintainer since 2005, with the organizational backing of ICANN. The tz database is also known as tzdata, the zoneinfo database or the IANA time zone database, and occasionally as the Olson database, referring to the founding contributor, Arthur David Olson.
Iran Standard Time (IRST) or Iran Time (IT) is the time zone used in Iran. Iran uses a UTC offset UTC+03:30. IRST is defined by the 52.5 degrees east meridian, the same meridian which defines the Iranian calendar and is the official meridian of Iran.
The time zone in Germany is Central European Time and Central European Summer Time. Daylight saving time is observed from the last Sunday in March to the last Sunday in October. The doubled hour during the switch back to standard time is named 2A and 2B.
Ireland uses Irish Standard Time in the summer months and Greenwich Mean Time in the winter period.
Antarctica sits on every line of longitude because the South Pole is on the continent. Theoretically, Antarctica would be located in all time zones; however, areas south of the Antarctic Circle experience extreme day-night cycles near the times of the June and December solstices, making it difficult to determine which time zone would be appropriate. For practical purposes time zones are usually based on territorial claims; however, the time zone of their supply base is often utilised. In most areas south of 80 degrees latitude, Coordinated Universal Time is assumed despite the limited presence of clocks.
As of 2022, daylight saving time is used in the following Asian countries:
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.
Switzerland uses Central European Time (CET) during the winter as standard time, 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).
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).
Time in Poland is given by Central European Time. Daylight saving time, which moves an hour ahead, is observed from the last Sunday in March to the last Sunday in October. This is shared with several other EU member states.
In Romania, the standard time is Eastern European Time. Daylight saving time, which moves one hour ahead to UTC+03:00 is observed from the last Sunday in March to the last Sunday in October.
Svalbard, an archipelago in the Arctic Ocean belonging to the Kingdom of Norway, uses Central European Time (CET) during the winter as standard time, 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). This is shared with the rest of Norway, as is Svalbard's use of daylight saving time, which the territory observes annually by advancing the clock forward on the last Sunday in March and back again on the last Sunday in October. However, as Svalbard experiences midnight sun during the summer due to being located north of the Arctic Circle, it gives daylight saving time no utility, and is only observed in order to make communicating with Norway Proper more convenient. At the 74th parallel north, the midnight sun lasts 99 days and polar night 84 days, while the respective figures at the 81st parallel north are 141 and 128 days.