Suspense depends on unreality of outcome. What circumstances at the beginning gave the man the confidence that he could make the trip safely? Where else in the story does he create suspense?

The man is very pragmatic. We know he has had experience in the cold because he seems to know what to do,

"Fifty degrees below zero stood for a bite of frost that hurt and that must be guarded against by the use of mittens, ear-flaps, warm moccasins, and thick socks. Fifty degrees below zero was to him just precisely fifty degrees below zero. That there should be anything more to it than that was a thought that never entered his head. "

The man, however, lacked "imagination". The suspense comes in because the man fails to recognize the signs that nature gives him. He pushes on and the reader senses his situation is more tenuous. The story soon becomes a struggle against life and death.

He was oblivious to the dangers. He did not have the knowledge about how cold it actually was and what that meant. He was not a deep thinking problem-solver, he just went about life cluelessly. He did not take people seriously. He laughed at the suggestion that it would be dangerously cold.