There is no way to see your Mac's CPU temperature in macOS. Not in Activity Monitor, not in System Settings, not in System Information. Apple has never shipped one.
That is not an oversight, and understanding why explains most of what is confusing about the apps that do show it.
Why macOS hides it
There is no public API for die temperatures. None. The two routes that exist are private C symbols you have to resolve at runtime, and the System Management Controller, a separate coprocessor you talk to through IOKit with an undocumented request layout.
Every temperature app on the Mac is using one of those two. That is why they occasionally disagree with each other, and why some of them break for a while after a major macOS release.
It also explains a second thing: your Mac does not have "a" CPU temperature. It has a lot of thermal sensors, and on Apple silicon the machine may publish a hundred or more plausible thermal keys. Any single number you see is somebody's decision about which of those to read and how to combine them.
Putting it in the menu bar
AirStats is free and open source and does this. Install it, open settings, and turn on CPU Temperature as a menu bar metric. It sits next to whatever else you have up there, and you can put it in the floating desktop overlay instead if you would rather keep the menu bar clean.
The number it shows is the mean of seven CPU die sensors. Reading every thermal key the machine publishes is possible and measured at around 19 ms per pass, which is far more time than a menu bar app has any business spending, so the sensor count is capped deliberately.
It reads them through the SMC, over public IOKit calls, and a read it cannot make is dropped rather than reported as zero. A monitor that prints a plausible wrong temperature is worse than one that prints nothing, because you will believe it.
If you want a temperature alert rather than a readout, threshold alerts will send you a notification when it crosses a line you pick, which is usually what people actually wanted.
What the number means
Higher than you expect, and that is usually fine.
Apple silicon runs warm by design and throttles itself long before anything is at risk. On an M3 Pro under a sustained artificial load heavy enough to hold the load average near 8, I measured a CPU die mean of 73.9 °C. That is a machine being deliberately hammered, and it is nowhere near a problem.
What is worth watching is not the peak. It is the shape:
- Warm under load, cool within a minute of going idle. Normal. Nothing to do.
- Warm at idle, and staying there. Something is running. Open the panel and look at top processes rather than at the temperature.
- Fans audible while temperature is unremarkable. Also normal on Apple silicon laptops, which spin up later and less than Intel Macs did.
The temperature is a symptom. Almost every time it is interesting, the actual answer is in the process list.