Waves of extreme heat have already swept across the United States, Europe and other parts of the world this summer. While people are most at risk in high temperatures, your Mac may be even more vulnerable. (People can be water-cooled, and no current Mac offers that option, though some have tried.) An iPhone or iPad will warn you when it detects it’s too hot before shutting down, while a Mac might just shut down suddenly . If it doesn’t shut down, you may be using it near its maximum capacity and causing a lot of extra wear and tear in the process of components that could later fail during other seasons.
Knowing the temperature is one thing. The other is how hot do your internal components have to run? Apple says you should only use a Mac if the ambient temperature (the temperature around you) is between 10° and 35°C and a humidity of 95 percent or lower.
Internal components produce much more heat than the ambient temperature, with around 100°F or 40°C, often the minimum they will operate under normal indoor conditions. CPUs, GPUs, ports, and other elements should not exceed approximately 192 °F (89 °C) for extended periods of time. At 100°C, the boiling temperature for water at sea level, you either need to figure out which energy guzzlers are making your computer work so hard or shut down the system for a while. (Hint: It’s almost always a browser.) You can use the Activity Monitor app in Applications > Utilities to look at Energy Impact in the Energy column for more information.
Check your Mac’s temperature
Modern Macs have an inordinate number of power sensors to detect problems and manage fan speeds in models that include them – I count 34 with one tool on an M1 Mac mini. These sensors can be monitored with the right knowledge or software.
On some Intel Macs, you can use Terminal or a free basic temperature monitoring utility. In Terminal, enter the following command and hit return:
sudo powermetrics –samplers smc |grep -i “CPU die temperature”
(Note that those quotes are straight double quotes.) Enter your administrator password when prompted. This provides a continuous temperature measurement of the temperature of the CPU. Press Control-C to stop monitoring.
You can also install the free Fanny app (not the most perfect name for Mac owners in the UK and other Commonwealth Macs), which offers a simple drop-down list of information in the menu bar or as a notification widget. Details include average CPU and GPU temperatures along with current fan speeds.
For any Intel Mac and M1-based Mac, the TG Pro utility ($20 but often retails for $10) provides detailed monitoring and fan control. You can see the temperature recorded by each sensor in your Mac and for hard drives and SSDs that support the industry standard SMART diagnosis. Information and controls are available in a standard app window as well as in a drop-down menu bar. That bar shows the highest port and CPU temperature and the current fan rotation.
TG Pro provides a tremendous amount of detail on demand and control of built-in fans, but uses color coding and a menu bar overview for an overview of the status.
You can also track the speed of internal fans and ignore Apple’s settings. This includes making rules for when fans and how fast fans run. The app comes with a preset rule that will spin the blades to their maximum rotation if the highest temperature of a CPU parameter is at least 70°C (158°F). Note: your MacBook Air does not have a fan.
Ask Mac 911
We’ve put together a list of the most frequently asked questions, along with answers and links to columns: read our super frequently asked questions to see if your question is there. If not, we are always looking for new problems to solve! Email yours to mac911@macworld.com, including screenshots where appropriate and if you’d like to use your full name. Not every question is answered, we don’t answer email and we can’t provide direct advice to solve problems.
