As part of its ongoing efforts to promote every single Pokémon out there, The Pokémon Company has shared special content dedicated to Flareon:
Did you know? Once it has stored up enough heat, this Pokémon’s body temperature can reach up to 1,700 degrees Fahrenheit. It stores some of the air it inhales in its internal flame pouch, which heats it to over 3,000 degrees Fahrenheit.
Source: The Pokémon Company