Fey Day was a holiday held in Waterdeep and the surrounding countryside during the vernal equinox on Ches 19. It celebrated the weakening of the barriers between Prime Material plane and the faerie realm of the Feywild.
Due to the increased proximity between the Feywild and the Prime Material Plane, the influence each realm had over the other was considered to be at its height. While rural areas were trepidatious and held many superstitions on this day (avoiding the forests, leaving confectionery treats on their porches, and the like), in Waterdeep it was a day of celebration.
The nobles hosted lavish masquerades, while the lower classes attired themselves in homemade disguises and went around soliciting temporary access into the celebrations in exchange for entertaining the crowds. Costumes included those of fey beings and Feywild rulers, such as Titania, Oberon, and Hyrsam. The joyous festival tended to be seen with scorn by some inhabitants who considered the practice foolish and preferred to stay at home during the event.