Forum Discussion
How come the "clock" is wrong by exactly one hour after every update?
After every Windows update, my PC's clock is exactly one hour fast or slow, even though it was correct beforehand. Could this be caused by daylight-saving settings, the selected time zone, or Windows time synchronization, and what should I check to keep the clock accurate after future updates without repeatedly changing it manually?
3 Replies
An exact one-hour difference usually points to the time zone or daylight-saving setting, rather than the clock itself losing time.
Right-click the taskbar clock and open Adjust date and time:
- Turn on Set time automatically.
- Check that the selected time zone matches your location.
- If automatic time-zone detection keeps choosing incorrectly, turn it off and select your zone manually.
- Where available, enable Adjust for daylight saving time automatically if your location observes it, then click Sync now.
Choosing the time zone manually still lets Windows synchronise the clock automatically. Don’t compensate by moving the clock forward or back an hour—that leaves the underlying setting wrong.
If it happens again, check whether the time zone or daylight-saving option changed. On a work-managed PC, IT may need to correct a policy that keeps restoring the wrong setting.
Check the time zone, and you can try:
Open the command prompt and run:
net start w32time
w32tm /resync
w32tm /config /update (update daylight-saving)
An error of exactly one hour almost always means a time zone or daylight saving mismatch, not a drifting clock. A drifting clock would be off by seconds or minutes. The usual causes, in order of how often I see them:
- Set time zone automatically is on, but location services are off or blocked. Windows then guesses the zone and flips it after an update. Check Settings > Time & language > Date & time, and either turn Set time zone automatically off and pick your zone yourself, or turn on Location services so it can detect it.
- Adjust for daylight saving time automatically is off, or your zone is wrong for your region. Make sure both the zone and that switch match where you are.
- Dual boot with Linux or macOS. Windows keeps the hardware clock in local time, Linux keeps it in UTC, so every boot into the other system shifts it by your UTC offset (and sometimes by exactly one hour around a DST change). Fix it by making Linux use local time (timedatectl set-local-rtc 1) or Windows use UTC with a registry value named RealTimeIsUniversal set to 1 under HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation.
- A low CMOS battery or an old BIOS that resets the clock, which updates and restarts tend to expose.
After you fix the zone, press Sync now under Additional settings, or run w32tm /resync as administrator. If it is still wrong after the next update, run tzutil /g to see which zone Windows thinks you are in.
