I had the same problem with my D. She didn't even want to wear a coat. An older male friend of mine told me that he had the same problem with his D. He is really laid-back,and told me, if she gets too cold at any time, she will learn and will finally wear a coat. He said that his D never learned but is still living to tell. Now, I'm not in such a cold climate as you are. So, maybe you can talk to her and negotiate. You can leave a heavy coat at school in case she really needs it for going outside. Like others have said, dress in layers.

Does she have any sensory processing issues? I myself hate wearing pants that are loose, it drives me crazy when I feel the material rub against my skin. I am very sensitive about hem lines and such in clothing and wonder if this is what your D is going through.. I worried and worried about my D but it all turned out fine. Have you tried getting her to wear leggings? They sell fleece leggings that are very warm. I hope this helps.