Recurring heat rash in cold weather. Causes?

Not likely heat rash. If your rash is occurring in cold weather, that is not likely heat rash. The term heat-rash refers to a rash occurring due to excessive heat. Eczema is often worse in cold and dry weather and so you may want to have it checked out. Without knowing what the rash looks like and its distribution on the body, it is difficult to make a diagnosis. So, consult doc. Good luck.