The poet has used barely two lines to depict the weather condition in the poem ‘The Cold Within’:

Six humans trapped by happenstance
In bleak and bitter cold.

So, it was bitter cold outside and quite understandably a chill winter night. Six persons were coincidentally and unfortunately ‘trapped’ in that difficult condition. The poet has used the adjectives ‘bitter and ‘bleak’ to describe the severe cold and bring a sense of urgency or emergency. Quite possibly everything around was frozen and life was not possible without the warmth of fire. That is why we see the men frozen to death in the morning as they did not share the logs they had to keep the fire burning.