I associate Sufjan (Illinoise and Michigan, anyway) with said seasons because it's composed with a lot of "icy" sounding keyboards, sleigh bells, cold sounding strings, and choir vocals. It always invokes a melancholy winter soundscape for me. This song pretty much epitomizes my associations:
I'm just wondering if anyone else associates certain artists with the colder months. Maybe it doesn't even sound like it, but you have personal experiences that make you think of winter.