Announcement: Microsoft Windows updates to daylight saving time and time zones now available on Automatic Update

As I posted previously on the December Updates to Daylight Saving Time and Time Zones, we have released a cumulative DST update for Windows operating systems, KB article 955839, December 2008 cumulative time zone update for Microsoft Windows operating systems.  This release replaces KB article 951072, and is now via Automatic Update (as of December 9, 2008), categorized as a roll-up and be included in the ITMU CAB.    

Additional time zone changes have been included since the previous cumulative update, including (in the form of Registry subkey name and (Display name): Argentina (Buenos Aires), Central Brazilian (Manaus), E. South America (Brasilia), Egypt (Cairo), Iran (Tehran), Israel (Jerusalem), Mauritius (Port Louis), Morocco (Casablanca), Pacific SA (Santiago) and Pakistan (Islamabad,Karachi).

We also published the new or modified TZI keys in an update to Microsoft KB article 914387 for IT professionals and sysadmins who may need that information.  Our goal is that our customers and partners can plan on rolling out and installing/ deploying these regular, scheduled cumulative update roll-ups as they are published.

Please note that KB 955839 also applies to Windows Vista and Windows Server 2008 in order to address the time zone changes in other countries.

As we update the Microsoft daylight saving time and time zone help and support pages at, I expect that other product teams at Microsoft will also provide information on their products and publish the associated documentation (KBs, blog posts) in the November and early December time frame.  Groups will note any changes and updates in their documentation, products and services, and guidance for their support teams and the field.

More DST and TZ product updates and guidance is available at and

As a reminder on our annual cadence (outlined here) and in a prior post, our product teams are moving to an annual product update cadence (with provisions for semi-annual as needed).  We recently posted the Microsoft Policy in Response to DST/TZ Requests, which addresses the established annual update schedule for Microsoft Windows has to cover changes in daylight saving time (DST) and time zone (TZ) releases. As noted, 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.

As I originally posted here, most Windows applications (and some services) reference the underlying OS for DST and time zone information, but some do not. The product and service groups with offerings that have internal DST or TZ references have agreed to follow the regular schedule for cumulative Windows OS DST & TZ updates. The regular Windows release provide a regular schedule for other product groups to follow, as noted in the DST & TZ Product Update Cadence policy. We hope that this will provide a more predictable way for our customers to anticipate and plan for our cumulative updates.

Let us know if you have questions.  And remember, the next daylight saving time change in the States and Canada is March 8, 2009.

Tags: Microsoft, Daylight Saving Time, Daylight Savings Time, RSS, DST, Mauritius, Morocco, Brazil, Pakistan.

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