Adelaide time zone and office-hour overlap

• UTC+10:30Australian Central Daylight Time, January
• UTC+9:30Australian Central Standard Time, July
• Australia/AdelaideIANA time zone name
• 0other listed cities on the same clock all year

Clock changes

Adelaide moves its clocks forward one hour on the first Sunday in October at 2:00 am local time and back on the first Sunday in April at 3:00 am, switching between Australian Central Standard Time (UTC+9:30) and Australian Central Daylight Time (UTC+10:30).

Adelaide is in the southern hemisphere, so its summer time runs from about October to April — the opposite half of the year from Europe and North America. For half the year the gap to London or New York is one hour wider than in the other half, with a few odd weeks in between.

Next change, as of when this page was built (2026-10-20): back on Sun 4 April 2027, from UTC+10:30 to UTC+9:30.

Sun and clock

At 138.6° east, the sun is highest over Adelaide at about 1:16 pm on the winter clock — 1 hour 16 minutes after noon, because the clock runs ahead of the sun.

In mid-January the sun rises at about 6:17 am and sets at about 8:32 pm — 14 hours 15 minutes of daylight.

In mid-July the sun rises at about 7:21 am and sets at about 5:22 pm — 10 hours of daylight.

On a January weekday, 0 of the listed cities share the whole 9-to-5 day with Adelaide, 76 share at least two hours and 138 share no office time at all; on a July weekday the counts are 1, 77 and 97. The furthest away on the clock in January is Honolulu (United States), 20 hours 30 minutes behind.

Of the 268 cities in this planner, 255 are behind Adelaide in January, 0 show the same time and 12 are ahead of it.

Cities on the same clock

None of the other 267 cities in this planner follows exactly the same clock as Adelaide through the whole year.

Only in July it matches Darwin.

Office hours shared with 12 business cities

Counting a 9-to-5 day, Monday to Friday, in both cities: Adelaide shares two hours or more with Los Angeles, Dubai, Mumbai, Singapore, Tokyo, Sydney and Auckland, and no office time at all with New York, London and São Paulo.

Time differences with Adelaide

• London and AdelaideAdelaide ahead by 8½–10½ hours · no shared office hours
• Sydney and AdelaideAdelaide behind by 30 minutes · 7 hours 30 minutes of shared office time

Adelaide on the half hour

Adelaide is one of the few large cities with a half-hour offset. In winter, from the first Sunday in April, it keeps Australian Central Standard Time at UTC+9:30; from the first Sunday in October it moves forward to Australian Central Daylight Time at UTC+10:30. The change is made at 2:00 am in October and at 3:00 am in April, as the clock-change rule above states. The half hour is the reason a table of whole-hour gaps never fits Adelaide: the planner uses quarter-hour columns so that its working hours line up with the neighbours correctly.

The nearest large neighbour is Sydney, which sits half an hour ahead of Adelaide all year, because both cities change their clocks on the same dates. A call between the two is therefore easy: shared office time is seven and a half hours, and 9:00 in Adelaide is 9:30 in Sydney. Darwin is the only listed city that shares Adelaide’s clock for part of the year; it matches in July, when Adelaide is on UTC+9:30 and Darwin, which never changes, is on the same offset.

Calling Asia and the Pacific

Singapore and Tokyo are the easiest partners outside Australia. Singapore is two and a half hours behind in January and one and a half in July, and Tokyo is one and a half hours and half an hour behind, which leaves roughly five and a half to seven and a half hours of shared office time depending on the season. Mumbai is five hours behind in January and four in July, giving three to four shared hours; Dubai is between six and a half and five and a half hours behind, with one and a half to two and a half shared hours. Auckland is ahead by two and a half hours all year and shares five and a half.

Europe and the Americas

The long distances are where Adelaide becomes difficult. London is ten and a half hours behind in January and eight and a half in July, and a nine-to-five day in each city shares no hour. Paris is nine and a half hours behind in January and seven and a half in July, with no shared time in January and half an hour in July. New York and São Paulo also share no office hour with Adelaide.

When 9:00 in Adelaide is 22:30 the previous evening in London, the realistic choices are an early start in Adelaide, which reaches the London evening, or a late call in Adelaide, which reaches the London morning. A sensible pattern is to alternate: one week the London team stays on, the next week Adelaide starts early. Los Angeles is a special case, with two and a half shared hours in January and half an hour in July, a difference that comes from the opposite seasons of the two daylight-saving calendars.

Southern hemisphere seasons

Adelaide’s summer time runs from October to April, so the gap to northern cities shrinks and grows in the opposite direction to what a European or American reader expects. When Europe goes back to winter time in late October, Adelaide has already been on summer time for a few weeks, and the gap to London becomes exactly one hour larger than it was in summer. In the northern spring the process reverses. For a few weeks around each change the gap takes an in-between value; check the weeks around the changes before booking a series.

Questions

Why are there fewer cities on the same clock as Adelaide than for most? Its offsets are unusual: no other listed city follows UTC+9:30 and UTC+10:30 on the same dates.

Is Adelaide ahead of Sydney? No. Sydney is half an hour ahead of Adelaide, in both seasons.

City names, coordinates and time zone assignments: GeoNames, licensed under CC BY 4.0 (selection and renaming of some cities by this site). Clock times are computed in your browser from the IANA time zone database. Sources and limits.