The Mac Observer

Skip navigational links

TMO Quick Tip - Prepping For the New Daylight Saving Time Change

by , 7:30 AM EST, March 2nd, 2007

As if it isn't already enough of a pain to set microwave oven and old VCR clocks, the U.S. government decided we needed a little more to keep us busy, so it changed the Daylight Saving Time dates on us. Even though you are most likely hosed with DST-aware VCRs, your Mac is a different story.

Mac OS X 10.3 and 10.4
If you are using Mac OS X 10.3.9 or 10.4.8, Apple is providing DST updates for the operating system and Java through its Software Update application. You can access Software Update by selecting Apple menu > Software Update.

Mac OS X 10.4.5 also includes updated DST time change information, but the update for Mac OS X 10.4.8 includes more recent time zone information.

Earlier Versions of Mac OS X
Mac OS X 10.2 and earlier versions of Mac OS X 10.3 don't have updates available for the new time change dates. If you are comfortable with rolling up your sleeves and doing a little Unix command line work in Terminal, there are options available for you, too.

New time zone database information is available at the Slackware Web site that you can use to update your Mac's time tables yourself. Instructions are included with the download.

If you aren't all that hip on trying the Slackware package, AFP548 is offering links to alternate patches for Mac OS X 10.2 and 10.3. These downloads include a disk image with the changed files and scripts to build the required source from those changes.

To verify your Mac's DST date change settings are correct type zdump -v /etc/localtime | grep 2007 at the command line in the Terminal application. The command returns the dates your Mac will use when switching DST settings. It should show March 11 and November 4.


Use Terminal to verify your DST date settings.

For those intrepid souls looking for even more knowledge about time zone and DST data, there is a wealth of information at the Sources for Time Zone and Daylight Saving Time Data Web site.

Old School
Not everyone is comfortable with command line action, and yes, there are still Mac users that rely on Mac OS 9.2 or earlier. If you fall into either of those camps, you'll need to start adjusting your Mac's clock manually, just like you do with that trusty old VCR.

In Mac OS X 10.3.8 and earlier do this:

  • Launch System Preferences. You can find it by choosing Apple menu > System Preferences.
  • Select the Date & Time Preference Pane.
  • Uncheck Set date & time automatically.

In Mac OS 9.2, do this:

  • Open the Date & Time Control Panel. You can find it by choosing Apple menu > Control Panels > Date & Time.
  • Uncheck Set Daylight-Saving Time Automatically.


Disable the automatic Daylight Saving setting in Mac OS 9.

About that old VCR... You're on your own.


Jeff Gamet is TMO's Morning Editor and Reviews Editor. He lectures, teaches and speaks on Mac OS X and design-related topics, and is the author of The Designer's Guide to Mac OS X from Peachpit Press.

if you have tips or tricks to share, or Mac-related questions you want answered.

Digg!

Observer Comments

Show: Subjects Only | Full Comments
Close Name:Guest
Subject: What changes happened between 10.4.5 and the 10.4.8 update?

Apple's KB article doesn't specify WHAT local changes happened in between the "National Standard" that is implemented in 10.4.5 and the update that is available for 10.4.8 (and 10.3.9) users.

Does anyone know?

Close Name:Guest
Subject:

None of this is a concern if you live in Arizona, which I do, thankfully.

In this, the information age, why the USA continues with observence of DST is just absurd. The concept is like a magician's sleight-of-hand trick, or a temporal version of robbing Peter to pay Paul. No one really gains anything.

Close Name:Guest
Subject: Watch it

I cannot help but chuckle quietly as I see all those wrist watches that change time automatically.....and have no way to update....makes me glad my watch still requires me to manually change it every month that has less than 30 days and every DST cycle. What were the IDIOTS in CONgress thinking?????????

Just call me Leemac

Close Name:Guest
Subject:

Quote
Guest wrote:
I cannot help but chuckle quietly as I see all those wrist watches that change time automatically.....and have no way to update....makes me glad my watch still requires me to manually change it every month that has less than 30 days and every DST cycle. What were the IDIOTS in CONgress thinking?????????

Just call me Leemac


Some wristwatches can be updated, but yeah, that's kind of funny. The government was thinking we're in tough economic times, there is a global war going on, and so we need conserve our resources more. After all, that's the point of DST in the first place.

Close Name:Guest
Subject: what is the purpose???????

Why are they extending the time zone??? Will it save me some $$$$?

Close Name:rezonate Posts: 741 Joined: 04 Feb 2005
Subject: Here's some more information

In case anyone was wondering, this site is a good summary of the big picture, from energy savings to the rationalle, even a little history.

If you have an atomic clock, set to detect DST automatically, the National Observatory master clock will send a DST signal at the right time and date, so no worries. Some watches pick up the master atomic clock signal, so no worries there. If your watch "knows" when the change *used* to happen, you can just turn off the auto setting and set the time yourself, just like your microwave, bathroom scale, and toaster.

If your VCR gets a time signal from the PBS station (like many do now), the PBS signal should set your VCR to the correct time. My VCR shows central time for some reason, even though I live in CA. And even though I set it to "manual time". Somehow the VCR always goes back to +6 instead of +8. Go figure.

Time to talk to William Andrewes about a sundial.

Close Name:gslusher Posts: 2088 Joined: 13 Nov 2002
Subject: DST

Quote
Guest wrote:
None of this is a concern if you live in Arizona, which I do, thankfully.

In this, the information age, why the USA continues with observence of DST is just absurd. The concept is like a magician's sleight-of-hand trick, or a temporal version of robbing Peter to pay Paul. No one really gains anything.


See the history of Daylight Saving Time (no "s") at Wikipedia and Web Exhibits, among other sources.

What DST does is to allow people to have more daylight time in the evening and less in the morning. People will get home from work and have more daylight time for family activities, for example. They'll also save money on electricity for lighting.

The same could be done if businesses switched their hours, but that would be chaotic, at best, paralyzing at worst.

One should note that the "time zones" in the US didn't come about until after World War I. Early railroad had a terrible time keeping schedules, as the local time at various towns and cities could vary, even for towns a few miles apart.

I lived in Arizona in the early '70s. The rationale for Arizona not going on DST had two parts:

1. It's "southerly," so the day length doesn't change as much over the year.

2. When California goes on PDT, Arizona, on MST, is the same. Arizona is at the western edge of the MST zone.

(It's also interesting that, apparently--see the map linked below, part of Arizona does go on DST. It's in the NE corner and may reprent a Native American nation.

There are other states where the line dividing time zones goes through the state. In Indiana's case, only a little bit of the NW corner (near Chicago) and the SW corner are in the Central time zone. Those do go on DST, while the rest of the state does not. (Here's a good map that shows time zones.

Close Name:Guest
Subject: Network Time for Mac OS Classic

There is hope for users still running Mac OS Classic! Check out this site:

http://www.marcelbrown.com/techbytes/2007/03/mac_os_classic_and_daylight_sa.html

Close Name:Small White Car Posts: 1960 Joined: 02 Jul 2004
Subject:

Quote
Guest wrote:
None of this is a concern if you live in Arizona, which I do, thankfully.

In this, the information age, why the USA continues with observence of DST is just absurd. The concept is like a magician's sleight-of-hand trick, or a temporal version of robbing Peter to pay Paul. No one really gains anything.


How, in the information age, can people still not know that DST saves energy? Tons of it. Others have already provided links so I won't bother, but it baffles me that some people still don't know that.

As for the computer clocks, I think we'll all be fine. The WORST thing that will happen is you'll have to reset your clocks twice. Annoying, but hardly the end of the world.

And correct me if I'm wrong, but everyone who has their clocks set to update itself based on some external server should be fine no matter what OS they're using, right?

Close Name:Guest
Subject: Mexico

Thanks for the command line info. I have all the latest DST updates in 10.4.8, but I am currently in Mexico and was worried my time would change on March 11th, but after trying your zdump I found my MacBook will do the right thing, change on April 1, as Mexico did not see fit to change with the US.

Thanks again.

Close Name:dhp Posts: 182 Joined: 22 May 2003
Subject: Time server

You don't have to worry about this if you set the OS (X or 9) to set the time automatically using a time server, do you?

Close Name:luomat Posts: 15 Joined: 16 Jun 2005
Subject: Will it save time?

Congress was so "sure" that this would save energy that they left the possibility open to change it back in 2 years time.

There was a real energy bill that was defanged and rendered mostly toothless by the US Government last year. Twiddling with DST isn't really expected to make that much of an impact, and I wouldn't be surprised to see it reversed in 2 years.

Close Name:rpaege Posts: 96 Joined: 16 Dec 2005
Subject:

Never mind that fiddling with DST pisses off your trading partners.

Close Name:Guest
Subject: DST Exception w/ GREP

They left one little thing out.
If you live in a State that doesn't observe DST, when you issue the GREP command in Terminal, you will get no results.
Really puzzled me, until I got the idea to change time zone from Hawaii to somewhere else, like Central Time Zone and then you'll get a result back, and you can see that your Mac is up-to-date.

Close Name:Guest
Subject: Atomic clocks

Dear Sir,
We have three atomic clocks and not one of them reset this morning to DST! We are on Central Time with signal coming from Colorado, I believe. (Computers are fine with the automatic patches.)

Any suggestions? Thanks. Jean

Close Name:Guest
Subject: atomic clocks

I found a explanation for the atomic clocks, cuz I've been searching all over since I have the same problem. looks like we just have to set our clock to a different time zone until it would usually do DST. hope this helps Tera


you have clocks that set the time automatically you will also need to check them to make sure that they have updated themselves correctly. Clocks that update themselves by coordinating with the atomic clock will update correctly, but some clocks have pre-programmed chips. If the clock was manufactured before the Energy Policy Act was passed two years ago, it will not update correctly. If you find that your clock has the wrong time you will have to reprogram it for a different time zone to compensate for the time change from March 11th to April 1st and October 28th through November 4th or the dates for the time change for the current year.

Comment on this Article


You cannot edit your comments.   You cannot delete your comments.

Comments are currently closed. Please email the author instead.


Recent Headlines - Updated November 22nd

Fri, 7:07 PM
Games - Soccer Sim Championship Manager 2010 Released for Mac
6:47 PM
Games - EA Publishes Original Monopoly for iPhone
6:15 PM
News - Original Apple I on Ebay for $50K, w/Letter from Steve Jobs
6:11 PM
Games - New iPhone Games: Secret of the Lost Cavern Ep 1, New DJ Nights, More
5:47 PM
Games - Star Trek D-A-C Game Headed to the Mac Next Month
4:57 PM
Product News - TidBITS Releases “Take Control of Syncing Data in Snow Leopard”
4:26 PM
John Martellaro's Blog - Particle Debris (week ending 11/20) Stationery Pads Go Poof
2:59 PM
Free on iTunes - Musée du Louvre, Art Lite, SketchBook Mobile X and More.
1:50 PM
Deal Brothers - Acer P215H bmid 21.5” Widescreen LCD Monitor:  $139.99
11:24 AM
TMO Appearances - Jeff Gamet Shares More Holiday Gift Ideas on MacJury
10:43 AM
Product News - Cocktail 4.5 for Leopard Adds QuickLook Cache Clearing
10:06 AM
News - Hack Enables Mac OS X 10.6.2 on Netbooks

The Mac Observer Reader Specials

  • __________
  • Buy Stuff, Support TMO!
  • Podcast: Mac Geek Gab
  • Podcast: Apple Weekly Report
  • TMO on Twitter!