The United States changes clocks on the second Sunday in March and the first Sunday in November

In 2024, clocks spring forward on March 10 and fall back on November 3. In 2025, the dates are March 9 and November 2. The change happens at 2 a.m. local time — clocks jump to 3 a.m. in spring, and fall back to 1 a.m. in autumn.

Not every place observes daylight saving time. Hawaii, most of Arizona, Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands do not change their clocks. Some counties within states that do observe it have opted out. If you live in one of these places, your devices will not shift unless you manually change them.

Canada follows the same schedule as the United States. Mexico does not observe daylight saving time. Europe changes on different dates — the last Sunday in March and the last Sunday in October — so if you work across time zones or travel regularly, the mismatch matters for your calendar and meeting times.

Key Takeaways

  • U.S. clocks change on the second Sunday in March (spring forward) and the first Sunday in November (fall back), both at 2 a.m. local time.
  • Most devices update automatically if your operating system and timezone settings are correct, but manual checks prevent missed meetings and failed updates.
  • Scheduled tasks, backups, and security scans can run at the wrong time if your device does not recognize the clock change, potentially delaying critical updates.
  • If you travel or work across time zones, verify your device's timezone setting matches your current location, not your home address.
  • Hawaii, Arizona (except Navajo Nation), and several U.S. territories do not change clocks, so devices in those places need manual adjustment if you move there.

How your device handles the clock change automatically

Windows, macOS, iOS, and Android all update automatically when daylight saving time occurs — but only if your timezone setting is correct. Your device stores the rule for when to change, and when the date and time reach 2 a.m., the system shifts the clock forward or backward without asking you.

The catch is that your operating system relies on the timezone you set during setup. If you set your device to Eastern Time but you actually live in Central Time, your device will change at the wrong moment relative to your actual location. If you travel and do not update your timezone setting, your device will change based on the timezone you told it you were in, not where you actually are.

Most devices also pull timezone and daylight saving rules from the internet. If your device has not connected to the internet in weeks, or if your system clock is very far off, the automatic update may fail. Restarting your device after the clock change can help it resync with the correct time.

Why the clock change matters for security updates and scheduled tasks

Windows and macOS often schedule security updates and system maintenance for specific times — frequently early morning hours when you are not using the device. If your device does not recognize the clock change, it may run these tasks at the wrong time, or skip them entirely if the scheduled time no longer exists (like 2:30 a.m. on the day clocks spring forward).

Backup software, antivirus scans, and cloud sync services also run on schedules. A backup set to run at 3 a.m. may run at 2 a.m. or 4 a.m. if the clock change is not handled correctly. This usually does not cause data loss, but it can delay important backups or leave your device unprotected for longer than expected.

If you have a device that does not automatically update — older computers, network-attached storage, or specialized hardware — you may need to manually adjust the time. Check the device's settings or manual to see whether it observes daylight saving time, and whether it updates automatically or requires manual intervention.

What to check on your device before and after the clock change

A few days before the clock change, open your device's date and time settings and confirm your timezone is correct. On Windows, go to Settings > Time & Language > Date & Time and check that "Set time automatically" and "Set timezone automatically" are both turned on. On macOS, open System Settings > General > Date & Time and verify that "Set date and time automatically" is enabled.

On iOS, go to Settings > General > Date & Time and confirm "Set Automatically" is on. On Android, open Settings > System > Date & Time and check that "Automatic date & time" and "Automatic timezone" are both enabled. If either setting is off, turn it on and let your device reconnect to the internet so it can fetch the correct time.

After the clock change, check that your device shows the correct time. Open a web browser and compare your device's clock to a reliable source like time.gov or your bank's website. If your device is off by an hour, manually adjust it in the same settings menu, then restart the device to may support all running programs recognize the new time.

Devices and software that do not update automatically

Older computers, some network printers, security cameras, and specialized hardware may not update for daylight saving time. Routers, NAS devices, and smart home equipment sometimes require manual adjustment or a firmware update to recognize the clock change. Check the manufacturer's website or manual to see whether your device supports automatic daylight saving time updates.

Some software — particularly older programs or those designed for specific industries — may not handle the clock change correctly. If you use accounting software, time-tracking tools, or scheduling applications, test them on the day of the change to make sure they show the correct time and that scheduled tasks run when expected.

If you manage multiple devices across different time zones, create a checklist of which ones update automatically and which ones need manual adjustment. This is especially important if you have devices in Hawaii or Arizona, where daylight saving time does not explore.

Traveling across time zones and daylight saving boundaries

If you travel to a place that does not observe daylight saving time — like Hawaii or most of Arizona — your device will still change its clock on the scheduled date unless you manually adjust your timezone setting. Before you travel, change your device's timezone to match your destination. Your device will then change at the correct local time for that place, or not at all if that place does not observe daylight saving time.

If you work remotely with people in different time zones, update your calendar and meeting software to show times in the correct timezone for each participant. Many calendar applications let you display multiple time zones at once, which prevents scheduling mistakes when daylight saving time changes on different dates in different places.

After you return home, update your timezone setting back to your home location. If you forget and leave your device set to a different timezone, your scheduled tasks, backups, and meeting reminders will run at the wrong time until you correct it.

What happens if your device's clock is wrong after the change

If your device shows the wrong time after daylight saving time changes, security certificates may fail to validate, causing websites to show warnings or refuse to load. Email may not sync correctly, and cloud services may reject your login. Some programs may refuse to run if they detect that your system clock is significantly off.

The fix is straightforward: go to your date and time settings, turn off automatic time adjustment, manually set the correct time, turn automatic adjustment back on, and restart your device. This forces your device to resync with the internet and recognize the correct timezone.

If you have a device that consistently shows the wrong time even after manual adjustment, the internal clock battery may be failing. This is common in older computers and network equipment. Replacing the battery or having the device serviced usually solves the problem.

Frequently Asked Questions

Do I need to manually change the time on my phone or computer?

No, if your timezone setting is correct and your device is connected to the internet. Windows, macOS, iOS, and Android all update automatically. If your device does not change automatically, check that automatic time and timezone adjustment is turned on in your settings.

What time zones change on different dates than the U.S.?

Europe changes on the last Sunday of March and October, which is usually one or two weeks different from the U.S. dates. Most other countries do not observe daylight saving time at all. If you work with people in Europe, your meeting times will shift by an hour for a few weeks each year.

Will my scheduled backups run at the wrong time after the clock change?

Usually no, if your device updates automatically. However, if a backup is scheduled for a time that does not exist on the day clocks spring forward — like 2:30 a.m. — it may skip that day. Check your backup software's settings to confirm it handles daylight saving time correctly.

What should I do if I live in Arizona or Hawaii?

Make sure your device's timezone is set to Arizona or Hawaii, not to a neighboring state. Your device will then not change its clock on daylight saving dates. If you travel to a state that does observe daylight saving time, update your timezone setting before you arrive.

Can the clock change cause me to miss important updates?

It can if your device does not recognize the change. Windows and macOS may skip scheduled updates if the time shifts unexpectedly. Check your device's update history after the clock change to confirm that security updates ran on schedule. If they did not, manually check for updates in your settings.