Way back when I was looking for a diagnosis, "stress" was considered as a possible cause for my symptoms (not just by my PCP, but also by me). I took a little getaway to North Conway NH, all by myself, a totally stress-free mini-facation.

It was mid-September, perfect weather--except no, there was a little heat wave. I was at the mall when I realized that I was having a real problem navigating, bumping into things, "wall-walking" in the stores, rubbery legs, brain soup.

That was the point where I knew, no, it's not just stress. There's something WRONG with me. I didn't know then that heat sensitivity was a common MS problem. I just knew that the hot weather was triggering problems that weren't normal.

I know others (that don't have MS) get tired of hearing me use "heat" as my excuse for staying inside but they truly cannot understand. Yes, I used to get hot on 90+ degree days but it didn't render me incapacitated. Now....it does. I just have to stay out of it.....and that means not even opening the front door.

Amen Kelly..

The very same thing happened to me, while attending a Sept. Fair. I already knew that the heat bothered me/my MS a lot, but, until that day, I didn't realize how much and to the horrible extent it would go. With the help of friends, I made it to my DH and car waiting, with A/C running. NeVeR did that again.

Oh how I wish I could click my heels and be anywhere just a little bit warmer right now.
In the middle of a super cold snap Antipodean winter with gallons of rain.
I'm chilled to the bone which personally I find much worse than the heat.
Roll on summer... shortest day has passed...
But all the same I can empathise with your humidity issues