Spring Forward, Fall to Pieces?

Will early daylight–saving time destroy your computer?

Remember when Y2K nearly destroyed Western civilization? I spent that New Year’s Eve at a huge techno rave party put on by young computer workers. A giant clock counted down the milliseconds to the new millennium and its prophesied moment of doom, but no one worried. As IT professionals, they knew the biggest problem might be bogus “1900” dates on their bank statements. Besides, the Australians and Japanese had already gone through Y2K hours before without a hiccup.

If nothing happened on Y2K, you can expect even less than nothing to happen this Sunday. That’s when, thanks to a new federal regulation meant to conserve energy, our clocks will spring forward three weeks earlier than they did last year. According to scaremongers, this change will trigger a “mini-Y2K.” A Time article, for example, warns that the time change will lead to “computer glitches that some fear could run to Y2K proportions.”

Y2K was supposed to bring the world to its knees. In practice, though, it was only a disaster for IT staffers who had to spend a year of overtime installing fixes. By the time the fatal date rolled around, my fellow techies had finished their work and were safely high as kites. Likewise, mini-Y2K will only be a mini-disaster for those same techies. Slate’s own computer people have been upgrading software and sending out careful instructions to minimize both the imaginary fears and the real problems this weekend’s Great Spring Forward will cause. But unlike Y2K, the DST change doesn’t have the potential to cause large-scale meltdowns. Here are three reasons why:

1. We had a practice run in 1986. Twenty years ago, many of the computer experts who now manage software development and IT operations had to deal with the last tweak to daylight saving time. As a result, mission-critical software and servers built since then—I mean the really big stuff like bank software, air-traffic control, and network routers—have been designed to accommodate DST changes. Better yet, most of these applications keep time in a single worldwide standardized format, usually the number of seconds since January 1, 1970. * Y2K was only a threat for software that predated the move to standardized time formats.

2. DST isn’t as big a bug as Y2K. If your computer believes the year has just shifted from 1999 to 1900, you’ve got a huge problem. If your computer isn’t sure whether it’s 9:00 or 10:00, you’ve got a much smaller problem. The systems prone to DST bugs are closer to you—personal computers, cell phones, PDAs—but smaller in terms of overall power. DST isn’t going to open the valves at the local nuclear plant or unlock the gates of the local prison.

3. You can do something about DST. The scary thing about Y2K was that it required centralized governments and giant corporations to do something, now. The DST bug, however, won’t affect the mainframes or embedded circuits at the local reactor—at least any more than it did in 1986. Since DST will affect the computers in your hand and on your desktop, you can take direct action yourself.

What should you do? If you’ve got a PC or two, go to and double-check the updates explained there. If you’ve got a Mac, follow these instructions. Palm and BlackBerry offer downloads for mobile customers, as do Nokia, Motorola, and nearly all other popular phone and PDA makers. A lot of dumber appliances—microwave ovens, coffee makers—don’t do DST at all, so you’ll have to reset them as always. No more or less of a problem than usual.

The problem gadgets are those few in-between items, the ones that try to guess DST correctly but can’t be upgraded with new rules to do so. I visited a publishing firm where the staff relies on handheld communicators for messages and scheduling. The company that makes them went bust after the boom fizzled, so no upgrades for DST are available. To prevent annual DST problems, the publisher will have to replace all of them sooner than planned.

Still, it’s likely that the worst thing that will happen to you next week is a couple of missed meetings. There’s an easy fix for that: Go edit your online calendar to include the correct time in the meeting’s subject line. That way if your computer uses the wrong timestamp, you’ll have it covered. And on Monday, wear a watch.

Correction, March 9, 2007: This piece originally stated that most essential software applications keep track of time by counting the milliseconds since January 1, 1970. They count the number of seconds. (Return  to the corrected sentence.)