what is the significance of the trail and the weather

The trail hadn't been used and the weather was deathly, freezing cold.

Day had broken cold and grey, exceedingly cold and grey, when the man turned aside from the main Yukon trail and climbed the high earth-bank, where a dim and little-travelled trail led eastward through the fat spruce timberland.

Fifty degrees below zero meant eighty odd degrees of frost.