I could never stand the sun hitting me in summer in our hot country Spain. Right now I’m at the beach and I’m either into the sea or under the umbrella but I don’t think in my case it’s MS related by that my skin is so so sensible to it. I get burned easily etc.
On the other hand I have read about the heat being bad for us but I’m running now in summer and while I avoid the hottest hours, I don’t feel specially bad because my body overheats.
I guess as everything with MS it’s different for each person.