Wowie, dowie!!! I thought that I was the only one with this condition. I have this experience, and even the seasons are the same: I am rather fluent in summer, and I have (or had) mild stuttering in the late winter. My story is that I stuttered from a wee lad until a week and a day before my 66th birthday. On June 7, 2021 I suffered a bad stroke and was in intensive care for a little over two weeks. I was pretty much "out of it" during that time, thinking that a colleague had inserted a computer program into my brain, etc. I certainly wasn't thinking about my fluency. So about 2 weeks after I got home, I was visited by a neurological nurse, this would have been early July (i.e. a "good" season). When she left, my wife said, "Do you realize that you were fluent the entire conversation?" So I think that I simply forgot that I stuttered. I've been reasonably fluent ever since. Go figure. I tried to bring the seasonal-ness of my (former) stuttering to the attention of a stuttering researcher, but he was not really interested. Maybe if we can identify even a small group of PWS who report seasonalness, it would catch the attention of researchers. My thinking is that maybe it would be interesting to do a full blood analysis of seasonal stutterers in the various seasons, and then look for small changes. Or maybe it is just another red herring.