I don't see this option in macOS, but can I set up a reminder for the two times a year the time changes. I need to reset the time in my camera. I could do this manually since the rules for DST keep changing.
I suppose the rules doesn't change that often, maybe it's the first or last Sunday of a month and I could figure that out in macOS.
Soapbox: let's just stay on Standard Time. There is plenty of evening daylight already with Standard Time.
Is there anything simpler/better than putting a reminder in your calendar? Not being facetious; that's what I do.
How many years do I go out? When will the rules change? First world problem. Eventually I'll forget.
But I've changed how I handle time changes in my camera many times over the years as the technology changes. I'm used to changing clocks, but changing the camera doesn't register.
Do you use Google for your calendar?
If so, you can try this:
If you're really determined, maybe you could do something with this API from timeanddate.com... "List all time changes (summer time / DST) in a specific country and query the start and end dates of DST changes".
Or you could scrape this page for "DST Started" and "DST Ends" perhaps?
UTC, you mean? Agreed. What's that, you're in the US? Just move to Arizona!
Complicated solutions are probably not worth the trouble unless you live in Australia...
"Australia has multiple time zones. Some of them are half-hour and quarter-hour time zones. Not all states and territories use Daylight Saving Time (DST)."
Time Zones... It's not even funny...
I wondered if you could perhaps run periodic checks on file timestamps and found this:
"Note that macOS doesn’t perform the clock change at the standard time, but that occurs some time afterwards, here with a delay of over 12 minutes. If you’re ever unsure whether those log entries are truly consecutive, or have merely lost an hour, examine the Mach ticks field in the log, as that should show no such discontinuity."
Other posts on the site have more about these "Mach ticks"... 
As of now, DST begins on the second Sunday of March and ends on the first Sunday of November.
Arizona is too hot!
I used to keep my camera on UTC, but then the iPhone app for the camera would set the time to whatever the phone was on. If I used the app all the time, no problem, but it's only occasionally. I then relabeled the photos using a file that I (tried to) keep up that logged when I changed time zones or when they were changed by others.
Yes, for the US (pending the Sunshine Protection Act being passed into law – so it could change) and Canada.
For European time zone changes, the corresponding dates are the last Sunday in March and the last Sunday in October (so there is extra complexity when converting to and from EDT etc.)
Here's one (untested) approach.
It sets a cron trigger to run on the first Sunday of November or second Sunday in March, checks the month when run and if it's November notifies you to stop DST otherwise to start it.
You might prefer to specify a particular time or repeating on the hour (0 * ...) with the cron.
Daylight Saving Reminder Macro (v10.2)
Daylight Saving Reminder.kmmacros (3.3 KB)
The problem with this approach is that the macro will fail if the Mac is not running when it needs to trigger...
In the Mac Calendar App you can do this two ways.
If you enable the "Holidays calendar" in Calendar>Settings>General, you will get a reminder one day before the clocks change.
Or/and you can set up your own repeating event using the same rules as the Holidays calendar. If in the future the rules change you can edit this recurring event.
The advantage of making your own recurring event is that you have more control of how it "reminds" you.
The last item on the list is "Custom..." and that gives you more options:
Calendar can send you an email. Or, the last of the options is "Open file" which can open any file on your Mac. It can even be used to open a Keyboard Maestro Trigger File... (in other words, the reminder can run a specific Keyboard Maestro Macro).
Is this not already included in Calendar? For the UK, at least, it comes up via the "UK Holidays" subscription, with an alert the day before. If nothing else you should be able to get the "rules" from that.
If you want a KM solution (and, again, speaking as an UK resident -- YMMV)...
Standard and Daylight are reported as different time zones by the %ICUDateTime% token. So all you have to do is compare the time zone now to the time zone this time tomorrow -- if they are different then throw an alert, add a Reminder, whatever. So something like this, run daily however you prefer, should work:
DST Test.kmmacros (5.5 KB)
Thank you. The alerts are grayed out on my calendar. But I did create my own with a specific reminder to reset the camera per @Zabobon.
mrpasini That's great. I wondered what the syntax of the time was and I guessed wrong, but see that KM read back the time setting in human readable form. Although the range setting for the date is more obscure.
Amazing what KM and this group can come up with.
I think the best way to handle that issue is to set the cron to run the macro every hour that day (or during a range of hours) by setting the second digit of the cron.
You can test a cron configuration at Crontab Guru. In this case, we're looking for a range that limits Sundays (not just dates) to the first and second weeks.
In fact, 8-15 is wrong (should be 8-14 because 15 might be the third Sunday). So here's a revision that displays the notification at 10 after the hour from 8a to noon on the Sundays the time changes:
Daylight Saving Reminder.kmmacros (3.0 KB)
Thank you for the update.
