my rear side mirror is frozen from icy rain?

[John]

I live in new york city and recently there has been alot of snow and icy rain, today when I was driving my car out of parallel parking, I noticed my rear side mirror, the mirror you used to check to see the car behind you, it has been frozen from last night freezing rain. which I can't see because I need those mirrors when I am driving to see cars behind me. What I did was used my finger nail to chirp it off, and boy did I regret it. I had blood underneath my finger nail, which taught me to never used finger nail again. So I am here because I want to ask someone how to defroze the icy rain that's on my rear side mirror. I don't want to used my finger nail again, I learn from my mistake. If anyone has any idea, I would be greatly appreciated. Thanks