I find extreme temps make it hard for me. Too cold or too hot and I can't breathe

Really depends on the person, and the state you live in. I have problems anytime the humidity & dew point are up, no matter what season.

Spring

Depends on the person. Some people really hate winter and others have a terrible time in the summer. Depends on how you react to things like cold or humidity. Ask a hundred COPDers and you'll probably get a fairly even split.

Jean

Your doctor is right I imagine, but if I only went out between 40 and 80 degrees, I would be inside most of the year, or a good part of it. If it is very cold, or very hot I do try to stay in, or at least limit my time outdoors.