I wonder whether it's the fluctuations in temperature or extremes or both. I feel it too. I can't speak for heat, because when it was hot in the summer, I was so generally unwell, I couldn't tell one trigger from another. But in the cold, which has suddenly come on, my hands in particular start to vibrate and just not warm up very easily. I mean, it goes away, but they're not very functional. I purchased thicker gloves that help keep them warm longer. Perhaps even worse is that my eyes tear much more and dry out much more quickly, and so itch. I always look like I'm crying when I'm out, especially if I'm riding fast on my bike. My nose also runs. I can't seem to hold on to my fluids, so to speak. But it could be worse...it can always be worse.