Iran Standard Time (IRST) or Iran Time (IT) is the

time zone A time zone is an area which observes a uniform standard time for legal, Commerce, commercial and social purposes. Time zones tend to follow the boundaries between Country, countries and their Administrative division, subdivisions instead of ...

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 The Iranian calendars or Iranian chronologies (, ) are a succession of calendars created and used for over two millennia in Iran, also known as Persia. One of the longest chronological records in human history, the Iranian calendar has been modi ...

and is the official meridian of Iran. Between 2005 and 2008, by decree of President

Mahmoud Ahmadinejad Mahmoud Ahmadinejad (born Mahmoud Sabbaghian on 28 October 1956) is an Iranian Iranian principlists, principlist and Iranian nationalism, nationalist politician who served as the sixth president of Iran from 2005 to 2013. He is currently a mem ...

, Iran did not 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, ...

(DST) (called ''Iran Daylight Time'' or ''IRDT''). It was reintroduced from 21 March 2008. On 21 September 2022, Iran abolished DST and now observes standard time year-round.

Daylight Saving Time transitions

The dates of DST transitions in Iran were based on the

Solar Hijri calendar The Solar Hijri calendar is the official calendar of Iran. It is a solar calendar, based on the Earth's orbit around the Sun. Each year begins on the day of the March equinox and has years of 365 or 366 days. It is sometimes also called the S ...

, the official calendar of

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

, which is in turn based on the

March equinox The March equinox or northward equinox is the equinox on the Earth when the subsolar point appears to leave the Southern Hemisphere and cross the celestial equator, heading northward as seen from Earth. The March equinox is known as the ver ...

(

Nowruz Nowruz (, , () , () , () , () , Kurdish language, Kurdish: () , () , () , () , , , , () , , ) is the Iranian or Persian New Year. Historically, it has been observed by Iranian peoples, but is now celebrated by many ...

) as determined by astronomical calculation at the meridian for Iran Standard Time (52.5°E or GMT+3.5h). This resulted in the unique situation wherein the dates of DST transitions didn't fall on the same weekday each year as they do in most other countries. DST started in Iran at 24:00 on 1

Farvardin Farvardin (, ) is the Iranian Persian name for the first month of the Solar Hijri calendar, the official calendar of Iran, and corresponds with Aries on the Zodiac. Farvardin has thirty-one days. It is the first month of the spring season (''B ...

, which corresponds to either 20 or 21 March in the

Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian cale ...

, depending on the precise timing of the equinox. (This is equivalent to 00:00 on 2 Farvardin, either 21 or 22 March.) Clocks moved forward at that time to 01:00 on 2 Farvardin (21 or 22 March). This spring change took place at the end of the day of

, which is the

Iranian Iranian () may refer to: * Something of, from, or related to Iran ** Iranian diaspora, Iranians living outside Iran ** Iranian architecture, architecture of Iran and parts of the rest of West Asia ** Iranian cuisine, cooking traditions and practic ...

New Year's Day In the Gregorian calendar, New Year's Day is the first day of the calendar year, January 1, 1 January. Most solar calendars, such as the Gregorian and Julian calendars, begin the year regularly at or near the December solstice, northern winter ...

and the most important festival in Iranian culture. DST likewise ended in Iran at 24:00 on 30 Shahrivar, which corresponds to either 20 or 21 September. (Equivalently, at 00:00 on 31 Shahrivar, either 21 or 22 September). Clocks moved backward to 23:00 on 30 Shahrivar (20 or 21 September).

Recent and upcoming dates

Time zone changes

References

{{Asia topic, Time in Time in Iran Time zones

Daylight Saving Time transitions

Recent and upcoming dates

Time zone changes

See also

References