Eggnog has traditionally been enjoyed warm, so it became associated with cooler weather. That coupled with its heavy ingredients, alcohol, and rich spices gave it even more of an association with the indulgences of the festive season. By the 1800s, eggnog had been established a primarily a holiday party drink, and manufacturers sell it according to that demand. So when the end of the year comes around it's the perfect time to enjoy a little holiday cheer! Happy holidays!