Laura, I know we have discussed hives before (my daughter is the one with chronic hives), but I don’t remember if you’ve taken yours to an allergist. If not, I would suggest it. What you are describing is known as physical hives, cold urticaria. (There are others, such as swelling from vibration, which I have experienced!) You may need to give her an antihistamine when she’s going to be out in the cold. It can also cause a reaction when swimming--suddenly entering cold water.