How Daylight Saving Time Affects Events

Many parts of the world (including most of the US and Canada) use Daylight Saving Time which means that the time changes twice a year. You'll want to make sure that your events are set up to handle this change as needed so your calendar is always displaying the correct start and end times for events.

The single best thing you can do to accommodate Daylight Saving Time is to use location-based time zones for all your events. This kind of time zone setting will adjust for DST, while a UTC-based time zone (e.g. UTC -8) is an absolute time and will not adjust for DST. If you choose to use a UTC-based option, you may need to manually adjust the time on your events.

We've got a full article all about Working with Time Zones to help you configure your site to meet your needs.

🔔 Series Engine users: Please reference this knowledgebase post to learn about event time compatibility with that plugin and the special setting they have for you to use.

How UTC time zones clash with DST: An Example Explained

Let's say your WordPress site time zone is UTC-5, but you have a recurring event whose event time zone is America/New_York. Some of the events happen before DST starts, some after. 

If the time zone mode is "Use site-wide time zone everywhere", then events will display as shown in the following screenshot:

DST Example
An example of events in a recurring event series happening before and after a DST change.

What's happened is as follows:

  • The first event happens in the America/New_York time zone before DST starts, so the clock time for that region is UTC-5
  • The next event happens in the America/New_York time zone after DST starts; for this region, DST changes its offset to UTC-4
  • So the first event is 8am UTC-5 in local time, while the second time is 8am UTC-4 in local time
  • Since the time zone mode is "Use site-wide time zone everywhere", the times will all display in terms of the site-wide time zone, which is UTC-5 in this case
  • So 8am UTC-5 will display as-is for the first event, because 8am UTC-5 = 8am UTC-5. But 8am UTC-4, the start time for the second event, will actually be displayed as 7am UTC-5, since 7am UTC-5 = 8am UTC-4
  • DST has made the event's UTC offset change from UTC-5 to UTC-4, but the site time zone is still UTC-5, so the times will display in terms of UTC-5

Other Examples

Time Zone Mode Site Time Zone Event Time Zone Expected Output
Site-wide UTC-5 New_York Screenshot
Local Event UTC-5 New_York Screenshot
Site-wide UTC-5 Los_Angeles Screenshot
Local Event UTC-5 Los_Angeles Screenshot
Site-wide New_York UTC-5 Screenshot
Local Event New_York UTC-5 Screenshot
Site-wide Los_Angeles UTC-5 Screenshot
Local Event Los_Angeles UTC-5 Screenshot

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