Daylight Saving Time – DST – Summer Time

Daylight Saving Time (DST) is the practice of setting the clocks forward 1 hour from standard time during the summer months, and back again in the fall, in order to make better use of natural daylight.

DST changes: Dates and local times

Clocks Back or Forward?

“Spring forward, fall back” is one of the little sayings used to remember which way to set your watch. You set your clock forward 1 hour in the spring when DST starts (= lose 1 hour), and back 1 hour when DST ends in the fall (= regain 1 hour).

Daylight Savings or Daylight Saving?

Northern Hemisphere

North America, Central America, Europe, Asia, northern Africa

Many countries in the Northern Hemisphere (north of the equator) use DST in the summer time, but not all. Daylight Saving Time usually starts in March-April and ends in September-November when the countries return to standard time.

Where will DST start or end next?

Southern Hemisphere

Australia, New Zealand, most of South America, southern Africa

In the Southern Hemisphere (south of the equator) the participating countries usually start the DST period in September-November and end DST in March-April.

More Than 100 Years

When Germany switched to DST on April 30, 1916 for the first time, it became the first country in the world to use DST on a national level. However, the town of Thunder Bay in Ontario, Canada implemented DST already in 1908.

DST statistics: Past and present use

Suggested Earlier

US inventor and politician Benjamin Franklin first proposed the concept of DST in 1784, but modern Daylight Saving Time was first suggested in 1895. At that time, George Vernon Hudson, an entomologist from New Zealand, presented a proposal for a 2-hour daylight saving shift.

Why Use DST at All?

Less than 40% of the countries in the world use DST. Some countries use it to make better use of the natural daylight in the evenings. The difference in light is most noticeable in the areas at a certain distance from Earth's equator.

Some studies show that DST could lead to fewer road accidents and injuries by supplying more daylight during the hours more people use the roads. Other studies claim that people's health might suffer due to DST changes.

DST is also used to reduce the amount of energy needed for artificial lighting during the evening hours. However, many studies disagree about DST's energy savings, and while some studies show a positive outcome, others do not.

Not Always 1 Hour

Today clocks are almost always set 1 hour back or ahead.

However, on Lord Howe Island, Australia, clocks are set only 30 minutes forward from LHST (UTC+10:30) to LHDT (UTC+11) during DST.

30 and 45 minute time zones

Throughout history, there have been several variations, like half adjustments (30 minutes) or double adjustment (2 hours). Adjustments of 20 and 40 minutes have also been used.

Topics: Daylight Saving Time, Timekeeping