What is thermalmonitord on a Mac, and how to check if your Mac is throttling
thermalmonitord watches temperatures and tells macOS when to slow down. pmset on our Mac had recorded no thermal or performance warning. How to check yours.
What is thermalmonitord?
It reads the Mac's temperature sensors and decides when the system must reduce performance to stay within safe limits. It lives at /usr/libexec/thermalmonitord and runs as root; ours used 2 to 3 MB and no CPU.
Is my Mac throttling?
pmset -g thermOn our Mac it printed: No thermal warning level has been recorded; No performance warning level has been recorded; No CPU power status has been recorded. When the Mac has been limited by heat, these lines show the level reached instead.
What should I do if it is?
- Use the Mac on a hard surface, not a bed or a lap.
- Find the app making the heat; see what is using the CPU.
- Avoid heavy work while charging in a hot room.
Throttling protects the hardware; it is not a fault. Persistent warnings on a cool desk with nothing busy are worth a check with Apple.
See it live
Free Mac's System tab ranks every process by processor use and energy impact, once a second, and marks the ones macOS will not let you quit as protected. See also WindowServer high CPU.
Related: secd and WindowServer high CPU.
Common questions
What is thermalmonitord on a Mac?
The macOS process that watches temperature and tells the system when to reduce performance.
How do I check if my Mac is thermal throttling?
Run pmset -g therm in Terminal. It reports any thermal or performance warning recorded.
Is thermal throttling bad for my Mac?
No. It protects the hardware. Frequent throttling on a cool desk is worth investigating.