Solution:
Root Cause: RTC Standard Mismatch Between Windows and Linux By default, Microsoft Windows assumes the motherboard Real-Time Clock (RTC/CMOS) stores time in
Local Time . Conversely, Linux (Ubuntu, Fedora, Arch, Debian) assumes the RTC stores time in
Universal Coordinated Time (UTC) . When you shut down Linux, its kernel writes current UTC time to the hardware clock. When Windows boots next, it reads the UTC value from the RTC, assumes it is already local time, and applies your local timezone offset *a second time*, shifting your clock by your UTC offset (e.g., -5 or +8 hours).
Diagnostic Verification: Open PowerShell in Windows and run: Get-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\TimeZoneInformation' -Name 'RealTimeIsUniversal'
If the property does not exist or equals 0, Windows is treating the hardware clock as Local Time instead of UTC. Step-by-Step Fix: 1 Open PowerShell as Administrator by pressing Win + X and choosing Terminal (Admin) or PowerShell (Admin) .
2 Execute the following command to create the RealTimeIsUniversal registry DWORD entry and set its value to 1:
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Reg add "HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation" /v RealTimeIsUniversal /t REG_DWORD /d 1 /f3 Disable the Windows Real-Time Clock update service lock (prevents Windows from converting back to local time on shutdown for 64-bit architecture):
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Reg add "HKLM\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient" /v SpecialPollInterval /t REG_DWORD /d 86400 /f4 Restart Windows Time service to load the new registry key:
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net stop w32time
net start w32time
w32tm /resync /force5 Reboot into Linux once, verify time with timedatectl, and then boot back into Windows. Both operating systems will now natively read the hardware clock as UTC without timezone shifting. For more details on registry configuration, see the Microsoft Official Support Guide . Prevention & Long-Term Monitoring: Keep RealTimeIsUniversal enabled. This setting persists across major Windows cumulative updates and provides the cleanest, standards-compliant fix for dual-boot configurations.