Changes to Daylight Savings Time

Impact of Daylight Saving Time changes in 2007

US Congress has passed an Act changing the dates for Daylight Saving Time in 2007 (the US Energy Policy Act of August 2005). The law goes into effect this year and the change expands DST by four weeks: DST begins on the second Sunday in March and ends on the first Sunday in November (previously DST began on the first Sunday in April and ended on the last Sunday in October).

DST change — effect on technology and computing systems

Any systems, software applications or electronic devices relying on DST information to properly use or display time will be affected by the US Congress’ DST change — for example, your Windows PC, your Outlook calendar, Blackberry devices, servers (e.g. Microsoft Exchange) and similar date-dependant applications. Without software updating from the application vendors, appointments and reminders may appear an hour later.

Outlook Calendar meeting invitations to external recipients

As there is no guarantee of what software external recipients are using, or if their applications have been updated, you may wish to enter the meeting’s time in the Subject line and/or body of the meeting invitation. Microsoft is recommending a similar workaround: “When a meeting is organized during the extended DST period, write the correct meeting time in the subject line or body of the message, e.g., ‘Project planning meeting – 8:30 am'”

Consider any calendar items in the Extended DST period to be suspect. If you are not sure, verify the correct time with the meeting organizer. NOTE: The DST change cannot be made by simply updating your PC’s clock.

Your Home PC

If you use a PC at home with the Microsoft Windows operating system, you may also want to ensure you run Windows Update in advance. To run Windows Update, you can visit – For example, if your home O/S is Windows XP, look for “Update for Windows XP (KB928388): Installing this update enables your computer to automatically adjust the computer clock on the correct date in 2007 due to revised Daylight Saving Time laws in many countries.”

Currently Microsoft has been listing this update in the Optional category of the Microsoft Update website, but may move it to the High Priority category as the DST change date nears. And if you also use Microsoft Outlook (not the free Outlook Express) at home, run the Outlook Time Zone Data Update tool (after the O/S update), available from the Microsoft Downloads.


To return to the main page of the blog, click here. To return to the blog Index, click here.

WordPress Themes