Certainly, things would have been easier if the movie had been filmed at a different time of year. However, since the idea of family is an important aspect of the film, the group of foster kids all needed to be there, and because a major sequence takes place at a winter carnival, a lot of the movie had to be shot at night. My set visit was a fairly cold experience during the day. I got to see the carnival set that David F. Sandberg refers to here but it was during the day, and as David F. Sandberg says here, it just wouldn’t have looked impressive on film.
Article source: https://www.cinemablend.com/news/2464997/making-shazam-a-christmas-movie-presented-all-sorts-of-challenges