The Winter Solstice is a day that usually falls on December 21st on the human calendar. It is considered the shortest day of the year.
In the EMPATH: The Luckiest Smurf story series, the Smurfs originally had celebrated the Winter Solstice in the same way that they currently celebrate the human holiday of Christmas: with festive decorations, singing, food, and the giving of gifts to each other. A yule log is burned every year on this day to ward away evil spirits in the village during the season.
Around the time of the Winter Solstice during Empath's first visit to the Smurf Village, Empath was lost in the forest and was found injured by the mysterious Wild Smurf, who had treated him. The other Smurfs eventually found Empath in the forest on the day of the Winter Solstice, though they did not find Wild Smurf, as he had hidden himself to keep the other Smurfs from finding out about him.
Around the time of a later Winter Solstice, Papa Smurf and Empath found a human boy by the name of Nicholas, who was lost in the forest, and helped him find his way back to civilization to rejoin his parents who were out looking for him. Nichloas thought that the Smurfs were little blue elves, and the particular appearance of their leader Papa Smurf had inspired him years later as a toymaker to dress in a similar manner when he delivered toys to the children of the villages every Christmas Eve.
The mini-story "Sharing Dreams Of The Holidays" takes place on the day of Winter Solstice.
Esther Smurfette Stories
In the Esther Smurfette story series, the Smurfs celebrate Winter Solstice with the annual Winter Ball, which Esther participates in.