User blog comment:Lightning the Skrill/Snow Wraith thermal vision gone wrong!/@comment-5690373-20150927215452/@comment-25962249-20151012085053

Dino's are neither warm nor cold blooded. And well, Dragons are sorta based on Dinos.... That being said, How to Train Your Dragon is fiction, with so many variety of Dragons it is not unlikely that some are warm blooded, some are cold blooded, and some are inbetween.