Like his father's Hellflame, Dabi's Blueflame comes from within the body but has a higher temperature output than Endeavor.

This is attributed by Endeavor to be because he was in a life-or-death situation, but a conversation in MHA chapter #387 ...

Dabi’s quirk, known as Blueflame in My Hero Academia, grants him the ability to generate extremely hot, blue flames capable of incinerating almost anything. His fire burns hotter than even ...