For the Hottest Coffee, Preheat Your Mug
Preheating ensures that most of the heat stays in your drink instead of being absorbed by the mug. To prove this, we conducted a test kitchen experiment.
If you like your coffee piping hot, it's a good idea to preheat your mug: Fill it with boiling water, let it sit for a few minutes, dump the water, and fill 'er up. Preheating ensures that most of the heat stays in your drink instead of being absorbed by the mug.