The weather reflects state of Scrooge’s heart, tracking his journey from cruel to kind
Weather is “cold, bleak, biting,” sometimes “piercing, searching,” the fog “dense.” - reflects Scrooge's demeanour
After Scrooge vows to change, the fog lifts and the temperature, while still cold, is now “clear, bright, jovial, stirring.” The sunlight is “golden,” the sky “heavenly,” the fresh air “sweet.”