The Widget version of Temperature Monitor is drop dead simple and even easier to use, though it’s limited to two sensors at a time.
All it takes a quick move of the mouse or trackpad pointer to bring up the Dashboard and you can see the Mac’s temperatures.
For even more detail there’s the Temperature Monitor app, which, depending on your Mac, gives you boatloads of temperature information and display features.
The list of functions is staggering. Not only can you display temperature sensors, you have complete control over how the information is displayed.
There’s even a historical graph layout of the Mac’s CPUs, graphics processor, logic board, disk drives, and much more.
The app version of Temperature Monitor (really, more of a suite of apps) displays up to eight current readings in the Menubar, but also shows readings on a floating window or as the Mac’s Desktop background image.
There’s even built-in alarms which can be triggered when your Mac reaches a certain temperature.
The app provides an amazing amount of information, all updated in real time and displayed in ways convenient to your needs. For most of us, the Mac and it’s inner workings are comfortably sealed and private, but information is valuable and Temperature Monitor gives you more of it than any other monitor app.