| You get steam coming out of the kettle, therefore that steam must be at 100 celcius.
The average temperature must be very close to 100 degrees celcius in order to get vigorous phase change to steam. (What we observe as boiling). This means that the majority of particles are above 100 degrees C (more properly, they have the energy relating to this temperature).
I'm unsure how a kettle detects the point at which it switches off, it's most likely a temperature sensor.
I hope this answers your question sufficiently. |