Australian Eastern Daylight Time

The choice of whether to use daylight saving time (DST) in Australia is a matter for the individual states and territories. However, during World War I and World War II all states and territories had daylight saving. In 1968 Tasmania became the first state since the war to practise daylight saving. In 1971, New South Wales, Victoria, Queensland, South Australia, and the Australian Capital Territory followed Tasmania by observing daylight saving. Western Australia and the Northern Territory did not. Queensland abandoned daylight saving time in 1972. Queensland and Western Australia have observed daylight saving over the past 40 years from time to time on trial bases.

New South Wales, the Australian Capital Territory, Victoria, Tasmania and South Australia observe DST every year. This has resulted in three time zones becoming five during the daylight-saving period. South Australia time becomes UTC+10:30, called Central Daylight Time (CDT), possibly with "Australia" prefixed (ACDT). The time in the southeastern states becomes UTC+11, using "Eastern" in the time zone name, Eastern Daylight Time (EDT), respectively Australia Eastern Daylight Time (AEDT).

Officially, the change to and from DST takes place at 2:00 am local standard time (which is 3:00 am DST) on the appropriate Sunday.

Of the states that observe DST, most began on the last Sunday in October, and ended on the last Sunday in March, until 2008. Tasmania, owing to its further southern latitude began DST earlier, on the first Sunday in October, and ended on the first Sunday of April.

On 12 April 2007, New South Wales, Victoria, Tasmania and the Australian Capital Territory agreed to common starting and finishing dates for DST. From the 2008/09 period, the start of DST in these states and in South Australia commences on the first Sunday in October and ends on the first Sunday in April. Western Australia became the only state to observe daylight saving from the last Sunday in October to the last Sunday in March. Since 2009 Western Australia no longer observes daylight saving.

Queensland (AEST UTC+10), Northern Territory (ACST UTC+9:30) and Western Australia (AWST UTC+8) do not observe DST.

Queensland has had a particularly involved debate over daylight-saving time, with public opinion geographically divided. A referendum on daylight saving, was held on 22 February 1992, following a three-year trial (1989/90 - 1991/92), and was defeated with a 54.5% 'no' vote. The referendum result displayed a distinct trend - that public opinion on daylight saving in Queensland is geographically divided, with the ‘no’ vote strongest in the north and west regional districts, while the ‘yes’ vote was strongest in the state’s metropolitan south-east.

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