All three movies benefited from holiday weekends early in their runs. The earlier in a movie's run a boosted hold is, the bigger the impact that it has on the total run of the film.
In Frozen's case, it's almost like the movie looped back to its second weekend, which is impressive in its own right. Frozen's sixth weekend could be bigger than its third, and it's not like it didn't have a big opening to begin with.
edit: I was predicting about $220M for this, just a smidge above Tangled. The trailers were weak and it looked too much like they were drawing from the same formula again.