There is also some speculation that Sauron may be able to manipulate the
snowstorms they encounter in the Misty Mountains. It's never clear how
much Sauron may or may not have power over Caradhras, just like his
relationship to the watcher and the Balrog are in question, but that statement
from "The Ring Goes South" is what inspired the sequence in the film in which
Saruman is waking up Caradhras (while Gandalf is trying to put him to sleep
again so he will settle
down).
Still round the corner there may wait
A new road or a secret gate;
And though I oft have passed them by,
A day will come at last when I
Shall take the hidden paths that run
West of the Moon, East of the Sun.
