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Daylight Saving Time Explained: When the Clocks Change and Why
Twice a year, most of North America and Europe move their clocks by one hour. In spring the clocks jump forward and you lose an hour of sleep; in autumn they fall back and you get it back. The idea is simple: shift an hour of daylight from the early morning, when most people are asleep, to the evening, when they are awake to use it.
When the clocks change
The dates are set by law, and they are not the same everywhere:
| Region | Clocks go forward | Clocks go back |
|---|---|---|
| United States & Canada | Second Sunday in March, 2:00 AM local | First Sunday in November, 2:00 AM local |
| European Union & UK | Last Sunday in March, 01:00 UTC | Last Sunday in October, 01:00 UTC |
| Australia (NSW, Victoria, ACT, Tasmania, South Australia) | First Sunday in October | First Sunday in April |
| New Zealand | Last Sunday in September | First Sunday in April |
Notice that the Southern Hemisphere runs the opposite way: when it is summer in Sydney, it is winter in New York. That is why the time difference between the US and Australia can change twice in a few weeks.
For the exact dates this year and next, see the daylight saving dates page, or the live countdowns to the next clocks going back and clocks going forward.
Why 2 AM?
In the US and Canada the change happens at 2:00 AM local time because it is the quietest moment of the week. Bars have closed, almost no trains or flights are departing, and the change does not move the date back into the previous day. In spring, 1:59 AM is followed by 3:00 AM. In autumn, the hour from 1:00 to 1:59 AM happens twice.
Europe does it differently: every EU country changes at the same instant, 01:00 UTC. That is 1 AM in London, 2 AM in Paris and 3 AM in Athens, so the time differences inside Europe never change.
Who doesn't use daylight saving time
- Arizona stays on Mountain Standard Time all year (except the Navajo Nation). See why Arizona doesn't change its clocks.
- Hawaii and the US territories (Puerto Rico, Guam, the US Virgin Islands, American Samoa, the Northern Mariana Islands) never change.
- Most of Asia and Africa, including Japan, China, India and South Korea, don't use daylight saving at all.
- Most countries near the equator skip it, because the length of the day barely changes through the year.
- In Canada, most of Saskatchewan stays on Central Standard Time all year.
How it changes time differences
Because regions change on different dates, the gap between two cities is not fixed. A few examples you are likely to run into:
- New York and London are normally 5 hours apart, but for about three weeks in March and one week around the start of November they are only 4 hours apart, because the US changes earlier in spring and later in autumn than the UK.
- Phoenix and Los Angeles have the same time in summer and are an hour apart in winter, because Los Angeles changes and Phoenix doesn't.
- New York and Sydney can be 14, 15 or 16 hours apart depending on the time of year.
Every time difference page on this site works these changes out for you, using the same time zone rules your phone uses.
Is daylight saving time going away?
It has been debated for years. In the US, Congress has considered bills to make daylight saving time permanent, and many states have passed laws saying they would switch to year-round daylight time if Congress allows it. Federal law currently lets a state stay on standard time all year (as Arizona and Hawaii do) but not on daylight time all year, so nothing changes unless Congress acts. The EU voted in 2019 to end the twice-yearly change, but member countries never agreed on which time to keep, so the changes continue. Clock Locations follows the official rules, and if they change, our clocks will change with them.
Tips for the changeover
- Phones, computers and smart watches update themselves. Oven clocks, car clocks and older alarm clocks usually don't.
- If you have a meeting with someone in another country in the weeks around a change, check the time again: their clock may not have moved yet.
- In spring, going to bed 15 minutes earlier for a few nights before the change makes the lost hour easier.
Quick answers
Do the clocks go forward or back in November?
Back. In the US and Canada the clocks fall back one hour at 2:00 AM on the first Sunday in November, so you get an extra hour.
Does Arizona change its clocks?
No. Most of Arizona stays on Mountain Standard Time all year. The Navajo Nation in the northeast of the state does change its clocks.
Why do the US and Europe change on different dates?
Each sets its own rules. Since 2007 the US has changed on the second Sunday in March and the first Sunday in November, while Europe uses the last Sundays of March and October.
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