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Reminder: Turn Your Clocks Back on Sunday, November 4

For Immediate Release: October 26, 2007

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Contact: NIST Media Group
(301) 975-2762

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Daylight Saving Time (DST) will end on Sunday, November 4, 2007, as determined by new rules implemented this year.

On November 4 at 2 AM local time, clocks should be set back one hour (to 1 AM local time) to switch from DST to Standard Time. (This does not apply to parts of the United States not observing DST.)

Before 2007, older rules had DST beginning later in the spring, and ending earlier in autumn. The Energy Policy Act of 2005 implemented new rules effective in 2007 to save energy by beginning DST on the second Sunday of March (March 11 in 2007) and returning to Standard Time on the first Sunday in November (November 4 in 2007), increasing the period of Daylight Saving Time by four weeks most years.

NIST provides accurate official U.S. time through a number of methods that include the new DST rules. You can get the official U.S. time for your time zone on the web at www.time.gov, through NIST radio broadcasts automatically setting radio-controlled timepieces to official U.S. time (http://www.nist.gov/physlab/div847/grp40/radioclocks.cfm), and through other NIST time services.

For more information about the new DST rules and NIST time services, see http://www.nist.gov/physlab/div847/dst.cfm.

Clocks on some computers using older operating systems may still be using the old DST rules. If you have such a system and have not yet updated your software for the switch to DST, information on the updating procedure is available at http://www.nist.gov/physlab/div847/dst.cfm.