Advisory: Samoa moving their time zone, traveling to the future

MC900189348[1]When is December 30th not December 30th?

When it’s 2011 in Samoa.

As you may have read, Samoa has decided to move ahead in time and join neighbors and trading partners on the western side of the International Date line (like Australia and New Zealand). In doing so, Samoa will move from December 29th directly to December 31st this year.

This from the Singapore Straits Times

“Samoa’s parliament has confirmed a plan to switch time zones so that it lies to the west of the international dateline, bringing its clocks closer to major trading partners in Australasia.

“Parliament on Monday backed Prime Minister Tuilaepa Sailele Malielegaoi’s plan to jump ahead by one day later this year, meaning Samoa will skip Friday, Dec 30, and move straight to Saturday, Dec 31. The prime minister said the change would facilitate business with Australia, New Zealand and Asia. Business is currently restricted to three trading days a week.”

So, this year, there will be no Friday, December 30, 2011 in Samoa’s history.

Technical Changes

The change will be a move from from UTC -11:00 to UTC+13:00, and a change in the display name for UTC +13:00 time zone (Nuku’alofa, Samoa). So, on the next clock tick after Dec 29, 2011 at 23:59:59, Samoa’s UTC offset becomes UTC +13:00. And the next clock tick will be is Dec 31, 2011 00:00:000. Cartographers will have some challenges dealing with all the updates to maps, moving the International Date Line to 171 degrees longitude west of Greenwich.

Associated challenges

There are also other technical challenges as I called out last year… as this change again occurs at midnite, but this time with good reason…

Here’s my regular advice for governments: in support of these types of changes, we provide guidance and Microsoft’s Policy in Response to DST/TZ Requests. It’s important for countries and territories to work towards seamless transitions to new DST and time zones policies, providing ample advance notice (of a year or more) with published confirmation of planned changes.

In addition – and this is important – we suggest that entities considering moves to DST implement changes at the next clock tick after 01:59:59 rather than at 00:00:00. Making the change at midnight can impact daily scheduled system events that sometimes occur at 12:00 midnite, such as back ups, data pulls or other automated tasks.

But I imagine that in Samoa’s case with this change, it would have been a greater challenge to have December 30th last only a few hours. Noting the article cites “there were 767 births and 43 marriages registered” on December 30th, I sympathize for the loss of a special day.

What’s Microsoft doing about this change?

Microsoft is aware of the upcoming change in time zone and shift in date for Samoa, and we’re looking at ways to minimize the impact this change has on our customers and partners. As with other changes to daylight saving time and time zones (like the impending change in Russia noted here), this will require an update to the OS. Most applications and services reference the underlying Windows OS for their TZ and DST rules, with some exceptions. This change in Samoa has the potential for worldwide impacts on time references for multinational customers. Updates will be important not only for users in Samoa but for connected systems around the world, particularly Samoa’s closest partners in the region. Further information will be shared here and reported on our official Daylight Saving Time Help and Support Centre at as status updates are available.


Tags: Microsoft, Daylight Saving Time, Daylight Savings Time, RSS, DST, Samoa

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