Eu altamente suspeitaria que o Ubuntu e o Windows discordassem sobre se o hwclock é localtime ou UTC. O conflito geralmente ocorre porque o Linux usa o hwclock definido no UTC, enquanto o Windows usa o hwclock definido para a zona localtime.
Se você quer que seu hwclock mostre a hora em seu fuso horário, então você precisará mudar o linux para não ser UTC, o que significa fazer com que o linux use o localtime. Se você está OK com o seu hwclock (BIOS) para estar em UTC, então mude as janelas para UTC.
Em aqui :
Make Windows use UTC
Note: This method was not initially supported on Windows Vista and Server 2008, but came back with Vista SP2, Windows 7, Server 2008 R2 and Windows 8/8.1.
To make MS Windows calculate the time from the hardware clock as UTC.
Create a file named
WindowsTimeFixUTC.reg
with the following contents and then double click on it to merge the contents with the registry:Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation] "RealTimeIsUniversal"=dword:00000001
Note: Windows Time service will still write local time to the RTC regardless of the registry setting above on shutdown, so it is handy to disable Windows Time service with this command (if time sync is still required while in Windows use any third-party time sync solution):
sc config w32time start= disabled
Reversing the change.
You can create a file with the following contents and then double-click it to merge in the original changes, as above:
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation] "RealTimeIsUniversal"=-
If Windows Time service was disabled, enable it again with the command:
sc config w32time start= demand
Make Linux use 'Local' time
To tell your Ubuntu system that the hardware clock is set to 'local' time:
Pre-Ubuntu 15.04 systems (e.g. Ubuntu 14.04 LTS):
edit /etc/default/rcS and add or change the following section
#Set UTC=yes if your hardware clock is set to UTC (GMT) UTC=no
Ubuntu 15.04 systems and above (e.g. Ubuntu 16.04 LTS): open a terminal and execute the following command:
timedatectl set-local-rtc 1