Get your sensors working

sensors --help will show the commands available.

For example, if you type sensors -f, it'll show the available sensors in Fahrenheit rather than Celsius.

But what if some of your sensors don't show up when you do that?

sudo sensors-detect will walk you through detecting all of the sensors available. Don't be surprised, if you're on a laptop, if it finds nothing because the sensors are controlled by ACPI rather than the OS.

If that's the case:
sudo apt install acpi

acpi -Vf