Comment 1 for bug 239782

If you have multiple operation systems installed, you have to use local time for your hardware clock for all operation systems or you have to use UTC for your hardware clock for all operation systems. It is not possible to mix local time and UTC for your hardware clock. Otherwise the times shift about hours if you switch to another timezone.

Ubuntu uses UTC for default, but Windows uses local time. If Ubuntu detects Windows while installing it changes to local time (setting UTC=no in /etc/default/rcS). If you install Ubuntu before Windows you have to change this setting manually.

In which order did you install Ubuntu and Windows?

If you installed Windows before Ubuntu, this is a bug in the installer. If you installed Ubuntu before Windows this "bug" cannot be fixed unless Windows uses also UTC for the hardware clock.