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 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 (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 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 (
Nowruz) 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, 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
Nowruz, which is the
Iranian New Year's Day 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
See also
*
Iranian calendars
References
{{Asia topic, Time in
Time in Iran
Time zones