Well it's obviously not a perfect analogy because of the structural and chemical difference, think of something like a marshmallow or a piece of ice. A frozen marshmallow is hard, a room temperature is more soft and squishy but both are not melted. Kind of similar to ice where it gets harder and more brittle as the temperature lowers. Temperature changes an objects structural integrity, and keep in mind this is after a lot of the building got hit by a plane and a lot of the load-bearing supports were destroyed.