Just trying to figure this out and see if anyone has any ideas.

I've been riding just about a year now. Did some nice rides in Hawaii that seemed pretty hot, but no problems at all.

Back at home, did a 50 mile ride and the temps were over 100 (maybe 103). I was well fueled and well hydrated, but late in the ride started having problems. I was getting cold chills. I broke out with goose bumps on my arms, and was cold. Even passing through a shady spot, I thought "what the heck?" it's over a hundred and can't be considered cold even in the shade. The chills would come and go every few minutes or so. It seemed to me that my body was having a hard time regulating it's temperature.

Same type of problem a few weeks later. It was a few degrees cooler, but still probably 98 or so. After about 30 miles I started getting cold chills again. I stopped and put on sun sleeves and drenched them in water. That seemed to help. But by the time I got home I was actually shivering.

Someone told me that using waterproof sunscreen could be the problem since I could not sweat properly to cool myself off. On the bike I sweat, but due to breezes on my arms and legs, it's usually only my head or my back area that gets wet. I suppose this could be the issue.

Anyone else have this issue? If you can't apply sunscreen what do you do?
While I don't have to worry about hot temps right at this moment, I would like to figure it out before summer. Just recently I've come to the time of my life when I'm starting to have hot flashes. Maybe I could get those to sync up with the chills and I'll be good to go