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https://help.ubuntu.com/community/UbuntuTime

Multiple Boot Systems Time Conflicts

Operating systems store and retrieve the time in the hardware clock located on your motherboard so that it can keep track of the time even when the system does not have power. Most operating systems (Linux/Unix/Mac) store the time on the hardware clock as UTC by default, though some systems (notably Microsoft Windows) store the time on the hardware clock as the 'local' time. This causes problems in a dual boot system if both systems view the hardware clock differently.

Make Linux use 'Local' time

To tell your Ubuntu system that the hardware clock is set to 'local' time:

edit /etc/default/rcS
add or change the following section

# Set UTC=yes if your hardware clock is set to UTC (GMT)
UTC=no