Sunday marks the arrival of Daylight Saving Time in the US and Canada

Clip art from Office OnlineSo if March 3, 2009, was square root day, is today international sum day? (030609, or 3+6=9)

Sorry, you’ll have to excuse me… it’s that time again.

That’s right: it’s the start of daylight saving time in much of Canada and the US this weekend, as noted in approximately 200 news articles today, one-tenth of what the hubbub was last year at this time.

"Huh?  It’s not for a couple of more weeks," a surprised exec exclaimed this week.

"Nope, it’s this weekend… we now update our products according to a semi-annual release schedule," I said. "You’re PC at home has likely been updated."

This year, DST in much of the US and Canada begins on March 8 in 2009, several weeks earlier than in years prior to 2007. As you may recall, in 2007 the US and Canada "sprang forward" a few weeks earlier than in past years in accordance with the US Department of Energy’s Energy Policy Act of 2005 that was passed into law. In 2009, DST will end on the first Sunday of November (in 2009, November 1); more details on the new DST start and end times can be found here). This results in a new DST period that is approximately three to four weeks longer than in previous years.

The Windows group established an annual update schedule for daylight saving time (DST) and time zone (TZ) releases. Most Windows-based applications (and some services) reference the underlying operating system for DST/TZ information, but some applications and services do not. Hence many of our product teams also follow an annual product update cadence such a Windows, with provisions for semi-annual cumulative updates as needed. For each update release, Microsoft accepts change requests up to a few months (generally four to six) prior to the release date. The Windows Release schedule provides a regular cadence for other product groups to follow.

So what should you do to make sure that your computers are ready for the change?  If you use Microsoft Update on your PC at home, chances are you’re already covered.  The 2008 Cumulative Time Zone Update for Windows was released in November to the Microsoft Download Center for currently supported Windows Operating Systems (including Windows XP, Windows Server 2003 and Windows Vista). This update can be found in KB article 942763.

This Cumulative Update for Windows should already be installed on your PC.  If you’re not sure, visit Microsoft Windows Update to check your PC and install important updates.  At work, if an IT Pro (aka ‘hero’) manages your network, chances are good that the needed updates have already been installed on your computers and devices automagically.

We’ve also updated our page on Microsoft’s Policy in Response to DST/TZ Requests, providing recommendations in order to achieve more seamless transitions to new DST and time zones policies. We suggest that governments should provide the following when considering changing DST or making adjustments to time zones:

  1. Ample advance notice (1 year or more) of the planned change.
  2. Official published confirmation of planned changes to DST or time zones.
  3. Concentrated efforts on promoting the change to the affected citizens.

If you manage servers and a host of Microsoft software, visit for more details.  And visit the support web sites of any other software companies to see if you need to apply any updates – it’s not just Microsoft software that may require updates.  Keep in mind that it’s not just the US and Canada that made changes to DST and time zones: we have an upcoming change in Australia and others noted on the DST and Time Zone Hot Topics page.

In most cases, customer will find that these changes have been addressed when the latest cumulative time zone update for Microsoft Windows operating systems was applied.  Some of the updates are not specific to the Australia Eastern and Central changes and can be applied immediately; other products (for example Office Groove) require manual adjustment after application of the time zone update to the host Windows operating system.

And remember: time is a precious thing. Never waste it.

Me? I’ll be sleeping in Sunday. I plan to change the clocks when I get up.


Tags: Microsoft, Daylight Saving Time, Daylight Savings Time, DST. 64,600,000 (up 62 million from last year); 6,950,000; 649,000+

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Note: updated links to KB955839 – thanks, Corrine!