When I turn my MacBook Air (M3) into full screen mode on any application, the notification center consumes 100% of the CPU, causing the temperature to rise to 60-70°C. In contrast, without full screen mode, the temperature remains at 49°C.
MacBook Air 13″, macOS 15.1
That is not unexpected. Generating the graphics for two monitors is a little bit of a chore and the processors will generate more heat in doing so.
The MBA is a fan-less design and depends on passive cooling, including using the aluminum chassis as a heat sink.
If the OS determines that temperatures have risen above acceptable levels, the CPU will throttle down to reduce the heat production. If things get really bad, the computer will shut down to protect itself.
Keep your Mac laptop within acceptable operating temperatures - Apple Support
MacBook Air M3 with hot temperature in full screen
