It was cold and raining here this morning. All of mine have access to shelter. I went out this morning to feed and MFM was standing outside in the rain. She was drenched, making it obvious that she had been out there for some time. BF has a mental break down if she is expected to get dripped on, let alone rained on. If she does get rained on she ends up shivering and carrying on. The old man you can never guess. Sometimes he acts like rain is lethal, other times he is out napping in it.
Do what your specific horse needs. Not what you would do, what your horse needs.