How do you change your screen's color temperature?

redshift -O 5000 works for instantly turning on warm mode instead of messing with location data

Redshift adjusts the color temperature of your screen according to your surroundings. This may help your eyes hurt less if you are working in front of the screen at night.

I'm not sure if this is what you need because, as far as I know, it won't let you adjust the colour temperature manually. It may help though, so Here's the website anyway.

If you've got any form of colour-calibration hardware (or can find a profile on the internet) then gnome-color-manager will load and apply monitor calibration system-wide.

Windows drivers for monitors and laptops will often come with an .icm colour profile you can use, which, while not perfect, would almost certainly be better than nothing.