Apparently Windows 10 gets confused about what time it is - I'm pretty sure that my BIOS clock isn't getting reset, as it's just fine under Linux, and the date portion is fine it's just the hours that are like... 4 or 5 hours off.
When I right click on the taskbar clock and click Adjust date/time, Set time automatically is already turned on. But when I turn it off and then on again, my time gets updated to the correct time.
How do I tell Windows to do this kind of thing for me automatically at boot?