The wild hunt: Åsgårdsreien (1872) by Peter Nicolai Arbo
The Wild Hunt was the hunting done by the pagan god odin, which took place in the most darkest times (nights) and the season of December. 
The evil troubles caused by the wild hunt during winter season:
The spirits of the dead, demons, and unclean energies surfaced the earth to trouble humans in the season of winter.
During the wild hunt the the evil acts of raping, activating dreams of horror, depression, putting people debt bondage, debtors to creditors, night mares, stimulating people into the acting of committing sexual immorality, group sex, divorce, causing conflicts of racism, antisemitism and hatred among people all took place in the season of December (yule tide). 
In fact Yule tide was celebrated as a sign of appeasing god Odin who led the wild hunt.

Odin’s dogs was barking louder and a second one fainter. Beside one or two shots, these barks were the only sounds that were clearly identified. When Odin’s hunt was heard, it meant changing weather in many regions, but it could also mean war and unrest. According to some reports, the forest turned silent and only a whining sound and dog barks could be heard.

The huntsmen were black, huge, and hideous, and rode on black horses and on black he-goats, and their hounds were jet black, with eyes like saucers, and horrible.

Seeing the Wild Hunt was thought to presage some catastrophe such as war or plague, or at best the death of the one who witnessed it.

Mortals getting in the path of or following the Hunt could be kidnapped and brought to the land of the dead. A girl who saw Wild Edric’s Ride was warned by her father to put her apron over her head to avoid the sight.

Others believed that people’s spirits could be pulled away during their sleep to join the cavalcade.

The passage of this hunt was also referred to as Odin’s Hunt. People who saw the passing hunt and mocked it were cursed and would mysteriously vanish along with the host.
Article taken from wikipedia.