When Hiccup and Astra discover the hidden world of dragons, they pan the dragons and they have 2 "White Fury"(s).
Earlier, Drago said Toothless and White Fury are supposed to be the last of its type alive.
There are several times where Toothless is seen in a cold environment , in animal house [ dragons , riders of berk ] Toothless and the other dragons protect Hiccup and the others when they get caught out in a blizzard , and in how to train your dragon 2 , Toothless falls into icy cold water when Hiccup is snatched off his back and survives that as well as playing with Hiccup in the snow and being in the dragon utopia with the other dragons which was built by an ice spitting dragon , but yet it's claimed that night furies can't survive in the cold , why would a dragon who can't survive in the cold stay in a cold environment .
Grimmel says that Night Furies can't survive in the cold , but in How to Train Your Dragon 2 (2014) not only did Toothless survive being in icy cold water but also was able to survive in the cold environment that he and Hiccup found themselves in as well as playing in the snow. However, it's possible that he simply does not know about the conditions Toothless could survive in, or he was just generally assuming all Night Furies can't survive in colder temperatures.
When Hiccup and the others leave berk with their dragons , they are carrying only one ship and nothing else , so where exactly did the supplies come from .