Uruguay to stop DST observance starting 2015

Disclaimer:  The information in this document is written in response to an announcement by the government of Uruguay about changes in the daylight saving time starting in the year of 2015.

The steps provided in this bulletin were created to mitigate the impacts that the daylight saving time changes will cause to customers. These are the impacts primarily anticipated at the time this document was written, and the effects that customers may face are not restricted to them.

The suggested actions on this document might receive additional testing. The information described in this document may change without notice.

In addition, customers should be aware that further guidance may be provided at any time by Microsoft.

Special notes: The official decree is published by the government on the following site: http://archivo.presidencia.gub.uy/sci/decretos/2015/06/cons_min_201.pdf

On June 29th 2015, Uruguay approved eliminating the Daylight Savings Time (DST) observance permanently. Back in 2004 Uruguay enacted a decree to establish DST in order to alleviate the country's energy crisis, and this year 2015 that decree has been repealed which effectively eliminates DST observance for Uruguay from this point on. The decision follows an initiative by the Chamber of Tourism to abolish DST in the country claiming that seasonal time change has an adverse effect on tourism.

An updated time zone, “(UTC-03:00) Montevideo” was changed in KB 3077715 - August 2015 cumulative time zone update for Windows operating systems. It was originally set to observe DST from the first Sunday of October through the last Sunday of March. However, according to the latest announcement from the Uruguayan government, this time zone will not observe DST any longer. Therefore, the previous DST rules for this time zone are removed in this update.

In addition to Microsoft products, other software, OS releases and hardware (phones, routers, switches and managed devices) may require updates and/or changes.

Our teams at Microsoft have taken several steps to alert customers and partners about this time zone update.

Microsoft will release August 2015 DST Cumulative Update KB 3077715 to address this change for all our supported operating systems: Windows Vista, Windows 7, Windows Server 2008, Windows Server 2008 R2, Windows 8, Windows 8.1, Windows Server 2012 and Windows Server 2012 R2. This update supersedes and replaces the update that is described in Microsoft Knowledge Base article 3013410, which was released in December 2014. All additional time zone changes that were released as hotfixes after update 3013410 was released are incorporated in this update.

General recommendations

  • For Windows 10 Install the KB 3093266: Cumulative update for Windows 10: September 30, 2015 and all other Windows versions install the August 2015 DST Cumulative Update KB 3077715
  • After installing this hotfix, Windows will have an update time zone: (UTC-03:00) Montevideo. You don’t need to change any time zone information on Date and time settings.
  • If you created appointments in the previous time zone rule, you can run the Time Zone Data Update Tool which will update calendars to accommodate the change in time zone rules. Single-instance and recurring appointments created with the previous time zone rule will be fixed to avoid offset of appointments, reminders, and calendar items.
  • Please note that if you adjust the machine’s clock manually, you may have adverse effects on your environment. This procedure is not supported by Microsoft.
  • If you moved your computer to another time zone as a workaround, you will need to perform additional steps to adjust your calendar. Please review the section below How to correct Outlook calendars to find out more information.
  • Contact Microsoft Support prior to any modification if you are unsure about the steps to follow in order to be prepared for the Daylight Saving Time change in Uruguay.

How to update Windows Servers and Desktop Operating Systems

For further information on how to update your Windows Operating system, please refer to the following article

914387 - How to configure daylight saving time for Microsoft Windows operating systems

How to correct Outlook calendars

Customer needs to follow the steps described on KB 931667 to update calendar items that occur during the extended DST periods for the following versions of Microsoft Outlook:
  • Microsoft Office Outlook 2007
  • Microsoft Office Outlook 2003
  • Microsoft Outlook 2002
  • Microsoft Outlook 2000

With Outlook 2010, Outlook 2013, and Outlook 2016, you may not have to run either the client side or Exchange server tool to rebase your calendar.  Starting with Outlook 2010, the client has a built-in dynamic time zone recalculation functionality. Meetings are displayed at the correct time on your calendar. However, if you also use an earlier version of Outlook or a mobile device to view your calendar, you may find the same meeting on your calendar is not displayed correctly because the underlying time zone information in the meeting is incorrect. In this case, please use the steps detailed in  KB 931667 to force a single meeting to be rebased by Outlook 2010 or above. Also, you can refer to the following article http://support.microsoft.com/gp/cp_dst “Daylight Saving Time Help and Support Center”.


Recommendations to minimize the impacts on Outlook/Exchange:

  • Simulate the changes on a lab environment, so you know what will happen and what to expect.
  • Work in conjunction with the operating system team to update the DST dates as soon as possible to minimize the chance of users creating new appointments before the hotfix is installed.
  • Before doing any change on the DST information, request the users to print their schedule so they have a reference to follow in order to manually update the appointments later if needed.
  • Take a full online backup of your Exchange Servers in case you decide to use the Exchange Calendar Update Tool.
  • For the meetings with multiple attendees only the meeting requestor should update the time and send the update to the others.
  • Include the time of the meeting in the e-mail request so that invitees can double check the correct meeting time (such as, "Project brainstorming - 11:00 A.M. Asuncion Time").
  • Exercise caution with the appointments and meetings created with the previous time zone rule. When in doubt, verify the correct time with the organizer.



941018 How to address daylight saving time by using the Exchange Calendar Update Tool

934001 A troubleshooting guide to the Exchange Calendar Update Tool (Msextmz.exe)

931667 How to address time zone changes by using the Time Zone Data Update Tool for Microsoft Office Outlook

943390 Some Outlook calendar items are rebased incorrectly when you use the Outlook Time Zone Data Update Tool to adjust for daylight saving time changes in certain time zones

Note: This is a "FAST PUBLISH" article created directly from within the Microsoft support organization. The information contained herein is provided as-is in response to emerging issues. As a result of the speed in making it available, the materials may include typographical errors and may be revised at any time without notice. See Terms of Use (http://go.microsoft.com/fwlink/?LinkId=151500) for other considerations.

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