Windows 10 always showing wrong time (when dual-booting with Ubuntu)

I had a similar problem on Dual Boot PC (Win 10 & Ubuntu 18.04). The issue was that Windows tries to keep hardware clock (a.k.a BIOS clock) at the local time, but Ubuntu tries to keep it at the UTC time. So the OSs fight each other, changing the hardware clock time each time they boot.

The solution is to either make Ubuntu use local time, or make Windows use UTC time. If you use Ubuntu 15.04 or newer, then I recommend the first option, because it's as simple as executing a single command:

timedatectl set-local-rtc 1

Do you have dual boot on your computer? I've had the same issue before and how i fixed it was to change something in GRUB customizer.There's also a way to change it in windows so it might help you!

Anyway this might help

I had the same issue.

(also windows 10, ubuntu dual boot)

Turned out the date was wrong in the BIOS settings.

Changing it there fixed the issue

I had a similar problem with a dual boot Windows 10 and ubuntu machine. Even though the clock was correct in the BIOS, and the time zone was correct in Windows, the clock was always one hour behind in Windows after rebooting. The only thing that reliably fixed it for me was to change the internet time server to pool.ntp.org. Neither time.windows.com nor time.nist.gov worked after reboots. I'm in the UK.

Also, make sure the Windows Time service is set to start automatically.

Open "Control Panel", click on "Clock, Language and Region", click on "Date and Time", select the "Internet Time" tab, select time.nist.gov from the dropdown, click "Update now".