Which time of year did Bruno arrive at Auschwitz in the boy in the striped pyjamas?

Bruno arrived at Auschwitz in the story "The Boy in the Striped Pyjamas" during the winter. His family's relocation occurs in the midst of cold weather, which is evident from the descriptions of the environment and the difficulties they face during the move. The winter setting helps to underscore the bleakness of their new surroundings and the stark reality of the camp.