Daylight saving time in the United States changed on March 10, 2024, and will change again on November 3, 2024

In the United States, daylight saving time begins on the second Sunday of March and ends on the first Sunday of November. That means clocks spring forward one hour in March and fall back one hour in November. For 2024, the spring change happened on March 10, and the fall change will happen on November 3. Most of your devices — phones, computers, tablets — update automatically if you have automatic time zone settings turned on.

The exact moment the change takes effect is 2:00 a.m. local time. At that moment, clocks jump to 3:00 a.m. in spring, or back to 1:00 a.m. in fall. If you are awake at that hour, you might notice your device's clock shift. Most people sleep through it and straightforward notice the sun is in a different place the next morning.

Not every state or territory follows daylight saving time. Hawaii, most of Arizona, Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands do not observe it. If you travel to or live in one of these places, or if you work with people who do, your device's time zone setting becomes more important — a mismatch can cause you to miss meetings or receive notifications at the wrong time.

Key Takeaways

  • Daylight saving time in the U.S. changes on the second Sunday of March (spring forward) and the first Sunday of November (fall back), affecting most devices automatically.
  • The change happens at 2:00 a.m. local time, so most people do not notice it happening, only the result the next morning.
  • Hawaii, Arizona, and several U.S. territories do not observe daylight saving time, so their clocks never change.
  • Devices with automatic time zone updates handle the change without your input, but manual time zone settings can cause your device to be off by an hour after the change.

Why the change matters for your device's security and updates

When your device's clock is wrong, security features and software updates can fail silently. Many security certificates — the digital documents that prove a website is safe to visit — are time-sensitive. If your device thinks it is 2023 when it is actually 2024, your browser may reject a valid certificate as expired, or accept a fake one as valid. This is one reason why keeping your system time accurate is part of basic security.

Software updates also depend on accurate time. When your device checks for updates, it compares the current time to the timestamp on the update server. If your clock is off by an hour, your device might think an update is from the future and refuse to install it. This can leave you running older software with known security holes.

The daylight saving time change itself usually does not cause problems if your device updates automatically. But if you have manually set your time zone, or if you travel and forget to update your location, you can end up an hour off after the change. Checking that your device is set to update time automatically is a straightforward way to avoid this.

How to check if your device updates time automatically

On Windows, open Settings, go to Time & Language, then Time. Look for a toggle that says "Set time automatically." If it is on (blue), your device will update when daylight saving time changes. If it is off, turn it on. You can also check "Set time zone automatically" on the same screen.

On macOS, open System Settings, click General, then Date & Time. Look for a checkbox that says "Set date and time automatically." If it is checked, your Mac will update. If not, check it. The same screen usually has an option to set your time zone automatically as well.

On iPhone or iPad, go to Settings, then General, then Date & Time. Look for a toggle labeled "Set Automatically." If it is on, your device will update when daylight saving time changes. On Android, go to Settings, then System, then Date & Time, and turn on "Automatic date & time" and "Automatic time zone."

What happens if your device does not update automatically

If automatic time updates are off and you do not manually adjust your clock after daylight saving time changes, your device will be one hour behind (in November) or one hour ahead (in March). This affects when you receive notifications, when your calendar shows meetings, and when your device checks for security updates.

The most common problem is calendar confusion. If your device is set to Eastern time but the clock is one hour off, a meeting scheduled for 3:00 p.m. will show as 2:00 p.m. or 4:00 p.m. depending on which direction the change went. You might arrive early or miss the meeting entirely. Email timestamps and file modification dates can also appear wrong.

If you realize your device is off by an hour after daylight saving time changes, the fastest fix is to turn on automatic time updates. Your device will correct itself within a few minutes. If you prefer to set the time manually, you can also open your device's time settings and adjust it by one hour.

Daylight saving time changes in other countries

If you work with people in other countries or travel internationally, their daylight saving time changes happen on different dates. The European Union changes on the last Sunday of March and October — different from the U.S. schedule. Canada follows the same schedule as the United States. Australia, New Zealand, and most of Asia do not observe daylight saving time at all, or observe it on completely different dates.

When you travel, the simplest approach is to keep your device set to "automatic time zone" rather than manually selecting a time zone. Your device will update based on its location, and when you return home, it will update again. If you turn off automatic time zone updates, you have to remember to change it manually every time you cross a time zone boundary.

How to set your time zone manually if automatic updates are not working

On Windows, open Settings, go to Time & Language, then Time Zone, and select your region from the dropdown. Make sure you pick the correct zone — Eastern, Central, Mountain, or Pacific for the continental U.S. If you are in a state that does not observe daylight saving time, like Arizona or Hawaii, select the zone that matches your location.

On macOS, open System Settings, click General, then Date & Time, and click the lock icon to make changes. Click the time zone field and type your city or region name. macOS will show you matching time zones. Select the one closest to your location.

On iPhone or iPad, go to Settings, then General, then Date & Time. If "Set Automatically" is off, you can tap the time zone field and search for your city. On Android, go to Settings, then System, then Date & Time, and tap Time Zone to select from a list of regions.

Frequently Asked Questions

Will my phone automatically change the time when daylight saving time happens?

Yes, if you have automatic time updates turned on, which is the default setting on most phones. Your phone will change one hour at 2:00 a.m. on the change date without any action from you. If you have turned off automatic updates, you will need to change the time manually.

What should I do if my device is one hour off after daylight saving time changes?

Turn on automatic time updates in your device's date and time settings. Your device will correct itself within a few minutes. If you prefer to adjust manually, open your time settings and move the clock forward or back by one hour depending on which direction the change went.

Do I need to change the time on my computer if I work from home?

No, if automatic time updates are on. Your computer will change automatically at 2:00 a.m. on the change date. If automatic updates are off, you should change it manually to keep your calendar, email, and file timestamps correct.

Why does my calendar show the wrong time for meetings after daylight saving time changes?

Your device's clock is probably one hour off. This happens when automatic time updates are turned off. Check your device's date and time settings and turn on automatic updates, or manually adjust the clock by one hour. Your calendar should show the correct times once your device's clock is accurate.

Do all U.S. states change their clocks on the same day?

Most do, but not all. Hawaii, most of Arizona, and several U.S. territories do not observe daylight saving time at all. If you work with people in these places, their clocks never change, so you may need to manually adjust for the time difference after the change happens in your state.