The purple and blue is supposed to tell us how cold it is, but Bernet's artwork (and the Rob Schwager coloring job) fights this somewhat since Bernet is drawing Hex in the same fashion whether is it summer or winter. Instead of communicating the coldness of the situation contained in the story within this issue, Bernet only tells us about the "snow torn edo" which flings Hex into the strange reclusion of his bounty target's world. Read a review of issue 65 Jonah Hex here.