If the coat is too short or not warm enough, you may be craving more love and affection than you are getting in waking life. According to Freud, the cloak is a symbol of female sexuality, but may also represent secrecy and concealment.
If a jacket features in your dream, this suggests the degree of formality with which you present yourself to others. A raincoat may suggest tears or the release of emotion.
If you are wearing a suit in your dream, this suggests the image you or other people have of you; the way you present yourself to others and different kinds of suits—wetsuits, bathing suit—represent different attitudes and situations.