Iran to set clocks back by one hour to observe DST

Iran will officially turn clocks back by one hour at midnight (1930 GMT) on Friday, September 21, readjusting to standard time after six months of practicing Daylight Saving Time (DST).

The shorter hours of daylight in the evenings will run until March 21, 2019, when Iranians will again advance the clocks forward by an hour.

In 2007, Iran’s Parliament passed a bill mandating the official time to be changed twice a year.

According to the bill, the country’s official time will be changed once at the beginning of the Iranian calendar year (on March 20 or March 21 on leap years) and once at the start of the second half of the Iranian year.

DST is the convention of advancing clocks by one hour so that evenings include more hours of daylight.

Typically, clocks are adjusted forward one hour in late winter or early spring and are moved one hour back in fall.

Governments often promote DST as an energy conservation measure on the grounds that it helps substitute natural summer sunlight for electric lighting.