I don't think that's the case anymore.
I just checked, the time in the UEFI BIOS is in UTC, yet both Linux and Windows 10 display the local time correctly as an offset to UTC. I didn't have to do anything special for that.
Edit:
So I looked a bit deeper into it, and this is apparently controlled by a registry key called RealTimeIsUniversal
in [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation]
. You can paste the text below in a .reg file and then import it to set the parameter:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation]
"RealTimeIsUniversal"=dword:00000001
I confirmed that this setting exists on my system, but I have no memory of ever manually setting this parameter. It's documented in the Arch wiki though, so it's possible that I did set it and forgot about it.
In any case, if you do a fresh Windows install and your time differs between Linux and Windows , this is what you should check.
Move your .weechat directory out of the way, to see if the problem is in your profile or with the weechat installation itself.