It looks like winter by the way people are dressed, but it's not really that cold.
"The celebration of Epiphany to enjoy the Rosca de Reyes is a Mexican tradition that takes place, 12 days after Christmas, each year in social reunions with family, friends or colleagues in offices or homes. This meeting is usually done a few days before or after January 6 at the offices or places outside the home, however for the family reunions they are normally held in homes on the sixth day of January in the evening, Epiphany Day or the appearance of the Wise Men or Magi Kings: Balthazar, Melchior and Caspar."
Yep. and there is a muñequita [doll] inside and if you get the muñekita you have to provide the tamales on February 2.