Is it reasonable for a doctor to recommend somebody with severe chronic pain syndrome to move to a warmer climate?

Yes: The reason why elderly people tend to be “snowbirds” , is that they feel better in warm weather. In my observations, it is the combination of cold and fluctuating air pressure but causes increased pain. Warm climates, such as the desert, have less changes in both temperature and air pressure. We are all familiar with people that can predict a storm coming by increased joint pain.