New updated page for coming Daylight Saving Time (DST) 2007 changes

As I noted here and here previously, the kick off for daylight saving time (DST) is changing this spring (2007). The start and end dates for the United States will transition to comply with the Energy Policy Act of 2005 (a US gov’t web site link). In short, DST dates in the United States will start three weeks earlier (2:00 A.M. on the second Sunday in March) and will end one week later (2:00 A.M. on the first Sunday in November).

In general, computer systems should be updated to reflect the new DST rules. For most customers, this means applying software patches to select Microsoft products, including various releases of the Microsoft Windows servers and operating systems, Microsoft Office and other applications. In a few important cases, customers must take more considered action, as outlined on our newly renovated DST 2007 website. ( This public page on the site will be revised regularly to include new product updates, compatibility information and links to Knowledge Base articles.

At the office and at home, my machines that subscribe to Automatic Update (which is all of our Window XP machines at home) received the Windows update, and my Windows Vista machines was just updated, too. 

Many Microsoft applications derive date and time information from the system clock, which “reads” the date and time information from the underlying operating system that it resides, so the changes need only be made to that underlying system. So you may not need to update many applications on your PC – check with your vendor to see if an update is required. For Microsoft products, many updates will be released through a combination of channels including Knowledge Base articles, Windows Update, Microsoft Update, Windows Server Update Services (WSUS), and the Microsoft Download Center.

Want to find out the accurate time in the US? Go to and select your time zone.

Select a time zone

“This public service is cooperatively provided by the two time agencies of the United States: a Department of Commerce agency, the National Institute of Standards and Technology (NIST), and its military counterpart, the U. S. Naval Observatory (USNO). Readings from the clocks of these agencies contribute to world time, called Coordinated Universal Time (UTC). The time maintained by both agencies should never differ by more than 0.000 0001 seconds from UTC (see recent comparisons).”

Tags: , , , , , .

4 replies on “New updated page for coming Daylight Saving Time (DST) 2007 changes”

There is now appearing much confusion at sites where not all Outlook clients connecting to an exchange server are either all on or all off the kb928388 DST update. I’ve confirmed and reported issues to Microsoft in my environment with this update and Outlook 2003 appointments, where they appear time shifted one hour, when viewed on a computer with Outlook 2003  with the patch and a computer with Office 2003 without the patch. The same is true when viewing appointments on Outlook 2003 with the patch and Outlook XP (regardless of patch level).

As previously mentioned, appointments will appear offset by an hour for the time period in March affected by the change in DST. Confusion sets in when the same calendar is viewed on patched and unpatched computers. I would suggest holding off any further deployment for as long as is necessary, or at least until the full ramifications of this patch in a mixed environment are realized.

If you haven’t seen this firsthand yet, a quick demo would be to create a 12 noon repeating appointment, running from Jan 1, 2007 to Dec 31, 2007 and view the same mailbox calendar, especially around the DST “adjustment” period, March 11 to April 1, 2007, and you’ll also see differences between an unpatched 2003 Client (or Outlook XP) and a Outlook 2003 client on a patched Windows XP machine.

As suggested, all clients connecting to the same mailbox calendar should be on the same Office Version AND the same patch level to view the appointment times, and all clients connecting to the same mailbox should all be updated at the same time (which is easier said than done).

The Exchange Server Message Store contains calendar items in Zulu/UTC time, and I believe time translation is done at the client level, within the OS (hence the effect of the patch) and can also be done within Outlook’s time zone setting option (which may well prove to need its own update, and not just the tool Microsoft is developing to run against the desktop Outlook client to correct for DST. I understand this tool will be similar to a new feature contained within Outlook 2007.

I don’t know how well a tool would work, given the confusion some of us are seeing when appointments are changed by several people, on different Outlook versions, and different computers with, and without, 928388 patch. Yes, as Microsoft has stated, please put meeting times within the subject line and warn your clients to pay particular attention to appointments in the period affected by the DST change.

Blackberry device calendars and their impact upon Outlook also seem to be affected to a different degree, and RIM informed me they are working on a patch, expected in late January or early February. I wonder how/if Windows Mobile is affected, and what impact 928388 may have upon those client’s Outlook clients’ and calendar syncing.

Will we have time to deploy the patch to all our clients, our Exchange servers, and patch all our blackberry devices before our helpdesk gets inundated with calls from upset clients with calendars that are off?

While I understand the tremendous amount of effort that goes into prepping and testing patches and updates, it upsets me that the change in DST was enacted into law in 2005 and less than two months before the change is to take effect, tools and patches aren’t ready. What will we do when we’re hit with the inevidable Zero Day? I hope it doesn’t come March 11th…I suspect I’ll be really busy that day…



Comments are closed.