Daylight saving time starts Sunday. What to know about 'springing forward.'

NBC News

08-03-2025

After a long winter of short days, it's finally time to spring forward.
Clocks across the U.S. will jump from 1:59 a.m. to 3 a.m. Sunday.
Here's what you need to know about daylight saving time and why we change the clocks twice a year in the U.S.
When does daylight saving time end?
Daylight saving time will start Sunday and last until Nov. 2. Standard time was in effect from Nov. 3, 2024, until Sunday.
The springtime clocks change differs from the fall. Unlike the fall, when we gain an extra hour and the clocks fall back, we lose an hour in the spring.
But that turns into longer days and brighter evenings as the spring and summer months begin. It will remain in effect until we turn the clocks back to standard time, which comes back into effect on Nov. 2 as we ready for winter and usher in an era of shorter days.
Why do we change the clocks?
The U.S. has been observing daylight saving time since 1918, with the establishment of the Standard Time Act, according to the U.S. Astronomical Applications Department. It was implemented in an effort to extend summertime daylight hours by pushing off sunset an hour.
Daylight saving time wasn't totally accepted when it was first passed — it was quickly repealed in 1919, making the changing of the clocks a local matter. The practice was officially re-instated during the early days of World War II and was observed from 1942-1945, according to the department.
Daylight saving time varied by state following the war and until 1966, when the Uniform Time Act passed, which standardized dates of daylight saving time, but allowed for states and localities to opt out of the practice if they did not want to participate.
Since that act passed, the standardized dates have been changed throughout the years, according to the department.
But the dates have remained the same since 2007. Since then, daylight saving time had started on the second Sunday in March and ended on the first Sunday in November.
Are there any states that don't observe the time change?
Yes. Residents in Hawaii and most of Arizona won't lose an hour of sleep Sunday night. The two states do not observe daylight saving time and do not change the clocks twice a year, according to the Astronomical Applications Department.
Is anyone trying to end daylight saving time?
The U.S. Senate passed the Sunshine Protection Act, which would make daylight saving time permanent year-round and usher out the era of changing our clocks, in March 2022. Under the bill, Hawaii and most of Arizona would continue to observe year-round standard time.
But the bill stalled in the House of Representatives, so the U.S. will continue to flip the clocks every six months until new legislation is passed in the House and Senate and then signed by the sitting president.
President Donald Trump addressed the practice this week when asked by a reporter when he is going to "get rid of" daylight saving time.
"I assume people would like to have more light late, but some people want to have more light earlier because they don't want to take their kids to school in the dark," he said, calling the issue "50-50."
"But a lot of people like it one way, a lot of people like it the other way. It's very even," he said. "And usually, I find when that's the case, what else do we have to do?"
Shortly after winning the election last year, Trump said he and Republicans would try to "eliminate" daylight saving time, calling it inconvenient and costly. It was unclear at the time whether he was referring to eliminating daylight saving time or making it permanent.
Almost all U.S. states have considered legislation to avoid changing the clocks, staying on either standard or daylight saving time year-round.
In the last six years, 20 states have passed bills or resolutions to codify year-round daylight saving time, according to the National Conference of State Legislatures. But since federal law does not currently allow year-round daylight saving time, those states are in a holding pattern until Congress passes the bill to make the change.
Is the U.S. the only country that changes the clocks?
No, many other countries observe some version of 'summer time,' whether that's daylight saving time or their own version. Not all do so on the same schedule as the U.S., though.
In the Southern Hemisphere, for example, the seasons are swapped, so the start and end date of 'summer time' are reversed from ours, according to the Astronomical Applications Department.
What do health experts say?
Some studies suggest that using daylight saving time year-round could reduce the number of traffic accidents and the amount of crime, but a number of experts are against longer days year-round.
According to some sleep experts, the sun should reach the highest point in the sky at noon, or solar time, which occurs during standard time.
A study from June 2022 found that people whose clock times weren't closely aligned with the sun had 22% higher road fatality rates than those living within 30 minutes of solar time.