Imagine how annoying it would be on a cold, rainy night to
build a warm fire, only to have your fireplace doused by
the storm. You could place a cap above the top of the
chimney to allow smoke to leave and prevent rain from
coming in. But then how would Santa get in?

A more common solution is to do nothing at all. Bricks are
exceptionally absorbent, which is one of the reasons
they're utilized in chimneys. Even large amounts of water
can be sucked into the brick and masonry before it has a
chance to extinguish the flame. The taller the building,
the more water is absorbed.