Spring forward, Fall back

Yes, it's that time of year again! Whenever the clocks change to adjust for the start or end of Daylight Saving Time (DST), we get a ton of support tickets from users asking why their shifts are askew and where the gaps and overlaps in their schedules came from. 

This mysterious behavior occurs when a group contains shifts in different time zones, and those time zones do not adjust to DST on the same date.

With DST changes just around the corner, you'll be happy to know that we've introduced new behavior into xMatters to warn you when you've got shifts in different time zones, so that you can prepare for any coverage gaps (or overlaps) that might occur in your on-call schedules.


When a user creates a shift, xMatters associates that shift with the user's time zone. For example, if Bob in London, UK creates a shift in a group, xMatters considers that shift to be in '(UTC+0000) Europe/London'. Likewise, if Mary from Vancouver, BC, Canada creates a shift in the same group, her shift is associated with '(UTC-0800) US/Pacific'.

Here's what the group looks like to Bob in London:


The times they are a changin'

London experiences the end of DST in October. At this time, Bob's 12:00 AM - 12:00 PM (midnight to lunch time) shift "falls back" an hour, starting on what used to be 11:00 PM the previous day. On Bob's view of the calendar, his shift continues to be from 12:00 AM - 12:00 PM before and after the DST change.

In Vancouver, the time change doesn't occur until November, so Mary's shift doesn't move relative to Bob's on the calendar. That means that as the London shift moves back an hour, it overlaps the end of the Vancouver shift by one hour, and there's a one-hour gap between the end of the London shift and the start of Vancouver's:


In November, when Vancouver observes the end of DST and changes their clocks back an hour, the offset shifts will realign; in the meantime though, you've got coverage gaps and overlaps in your on-call schedules.

The solution

Now that you know more about why this funny business is happening with your shifts, let's talk about what you can do to work around it. You've got a couple of options:

  • Adjust the shifts to cover the gaps and remove the overlaps.
  • Create a new shift that covers the gaps until Vancouver's time changes.

How we can help

It's important to us that you're not caught off-guard the next time DST changes occur, and that you don't experience coverage gaps in your on-call schedules.

To address this issue, we've updated xMatters On-Demand to detect if your groups contain shifts in different time zones and to warn you before a time change occurs so that you can proactively update your shifts.

You can expect to see alerts like this popping up in your calendar on October 10th:


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  • Was this banner introduced? I don't think we saw one ahead of last weekends DST change. 

  • Hi Peter,

    The banner would only show if there are shifts in the same group that were created in different timezones.