Time zones in the US change twice a year, on the second Sunday in March and the first Sunday in November

In March, clocks move forward one hour at 2 a.m. local time — this is called Daylight Saving Time (DST). In November, clocks move back one hour at 2 a.m. local time, returning to Standard Time. The exact dates shift slightly each year because they are tied to specific Sundays rather than fixed calendar dates.

Not every state observes this change. Hawaii and most of Arizona stay on Standard Time year-round and do not shift their clocks. US territories including Puerto Rico, Guam, and the US Virgin Islands also do not observe DST. If you live in one of these places or travel to them, your local time will not change on the national changeover dates.

Key Takeaways

  • Clocks spring forward one hour on the second Sunday in March and fall back one hour on the first Sunday in November.
  • Hawaii, most of Arizona, and US territories do not observe Daylight Saving Time and keep the same time year-round.
  • The time change happens at 2 a.m., so most people experience it when they wake up rather than during the day.
  • Devices that connect to the internet — phones, computers, smart home systems — usually update automatically, but some clocks and appliances may need manual adjustment.

Why the US changes time twice a year

Daylight Saving Time was introduced to make better use of daylight during longer days. The idea is that shifting an hour of daylight from morning to evening reduces energy use for lighting. The practice began during World War I and has been used on and off since then.

The current system — changing on the second Sunday in March and the first Sunday in November — has been in place since 2007. Before that, the dates were different. Some states and regions have pushed to stop changing clocks altogether, but federal law currently requires most of the country to observe DST unless a state has chosen to stay on Standard Time year-round.

Which devices update automatically and which do not

Smartphones, computers, and tablets connected to the internet update their time automatically when the change happens. You do not need to do anything — your device will show the correct time when you wake up on changeover day. Smart home devices like Alexa speakers and Google Home also update on their own if they are connected to Wi-Fi.

Devices that do not connect to the internet — wall clocks, car clocks, microwave displays, oven clocks, and older alarm clocks — will not update automatically. You will need to change these by hand. Some car clocks have a manual adjustment button or menu option; check your vehicle's manual if you are unsure how to change it. For wall clocks and appliances, you simply turn the clock forward or backward as needed.

If you have a smartwatch or fitness tracker, check whether it is set to update automatically in its settings. Most newer models do, but some older ones may not.

How to prepare for the time change

A few days before the change, make a list of clocks and devices in your home that do not update automatically. This includes bedroom clocks, kitchen clocks, car clocks, and any appliances with time displays. On the morning of the change, or the night before, go through and adjust each one.

If you have a routine that depends on a specific time — taking medication, catching a bus, attending a meeting — pay extra attention on changeover day. When clocks spring forward in March, you lose an hour of sleep, which can affect how you feel. When clocks fall back in November, you gain an hour, which some people find disorienting if they are used to a set schedule.

If you work with people in other time zones or have meetings scheduled across regions, double-check the time of any calls or events on changeover day. A meeting scheduled for 9 a.m. in New York will be at a different time in Arizona (which does not change) or Hawaii.

Time zones that do not change

Hawaii observes Hawaii-Aleutian Standard Time year-round and does not shift to Daylight Saving Time. Most of Arizona does the same — the state stays on Mountain Standard Time. The Navajo Nation, which spans parts of Arizona, New Mexico, and Utah, does observe DST, so some areas within Arizona do change their clocks.

US territories — Puerto Rico, Guam, American Samoa, the Northern Mariana Islands, and the US Virgin Islands — all stay on their standard time and do not observe DST. If you travel to any of these places or call someone there, remember that their time will not match the mainland US time on changeover dates.

What to do if you miss the time change

If you forget to change a clock and realize it hours later, simply adjust it to the correct time. There is no penalty or consequence for being an hour off. If you show up to an appointment an hour early or late because you forgot the change, let the person know what happened — most people understand that the time change causes confusion.

If you have a recurring appointment or alarm set for a specific time, check it on changeover day to make sure it is still set correctly. Some calendar apps and alarm clocks may not update properly if they were set before the time change was announced.

Frequently Asked Questions

Do I need to change my phone's time manually?

No. Phones connected to the internet update automatically when the time change happens. If your phone is not connected to Wi-Fi or cellular data, you may need to update it manually through the date and time settings. Check your phone's settings to confirm that automatic time zone updates are turned on.

What time should I set my clocks to on changeover day?

In March, move clocks forward one hour — if it is 2 a.m., it becomes 3 a.m. In November, move clocks back one hour — if it is 2 a.m., it becomes 1 a.m. Most people do this the night before or the morning of the change, depending on what is convenient for them.

Why does Arizona not change its time?

Arizona opted out of Daylight Saving Time in 1968 and has stayed on Mountain Standard Time year-round. The state found that the extra daylight in the evening during summer months did not provide enough energy savings to justify the disruption. Hawaii made a similar choice for its own reasons.

If I travel across time zones on changeover day, what time is it?

Your device will show the correct local time for wherever you are. If you fly from New York to Arizona on the day clocks spring forward, your phone will automatically adjust to Arizona time, which is two hours behind New York and does not change. If you travel to Hawaii, your phone will show Hawaii time, which is three hours behind Arizona.

Can I turn off automatic time updates on my phone?

Yes, but it is not recommended. You can disable automatic time updates in your phone's date and time settings, but doing so means you will need to manually update your time twice a year. Most people leave automatic updates on to avoid confusion.