The Location Services Bug
macOS relies on Apple’s Location Services to determine where you are in the world and automatically adjust your computer’s clock to the correct local time zone. For frequent flyers, this is a magical feature. However, if you are sitting at home and your Mac suddenly decides it is located in London instead of New York, causing your clock to jump forward five hours and throwing off all your calendar alerts, the system is misinterpreting its location data (often due to a VPN, a newly installed Wi-Fi router, or a general ISP routing error). When the automatic system fails, you must take manual control.
How to Disable Automatic Time Zone Detection
You can force macOS to respect a specific, fixed time zone regardless of what its Wi-Fi antennas or Location Services tell it.
1. Click the Apple logo () in the top-left corner of the menu bar.
2. Select System Settings (or System Preferences on older Macs).
3. In the left-hand sidebar, click on General.
4. In the main pane, click on Date & Time.
5. Locate the toggle switch labelled Set time zone automatically using your current location.
6. Click the toggle switch to turn it Off. You may be prompted to enter your Mac administrator password to authorise this change.
Setting the Correct Zone Manually
As soon as you turn off the automatic setting, the “Closest City” dropdown menu directly below it will unlock and become clickable. Click this dropdown menu, type the name of your nearest major city, and select it from the list. Your Mac is now permanently locked to that specific time zone. Your clock will still automatically stay perfectly synced to the precise minute and second via Apple’s internet time servers, but it will never randomly jump hours ahead or behind again.