Are these hives?

You might have a sun sunsitivity. My mother in law turns all blotchy when exposed to the sun so she tries to avoid the sun as much as possible. Have you added anything new lately such as a new sunscreen, lotion, soap etc? What happens when you do try sunscreen, do you still get red and itchy? Hives sometimes have no rhyme nor reason as to why they pop up and disappear but if this persists, I think you should go see your doctor, dermotologist or allergist.

I would say no, but I'm no doctor. Definately have it checked out if it keeps happening. Moist heat makes me think of a yeast infection but then your rash would be constant and not just apparent in sunlight. Have you tried any OTC anti itch creams yet? When I went on vacation a few weeks back, I got covered in chigger bites. I found a Benedryl spray and I couldn't believe how effectively it worked. Now I swear by that stuff, it's great.

TickSquisher
I don't think it's a heat rash as there are no raised areas, just red blotches. We've had cooler weather the last week and it seems to have gone away. I've also been staying out of direct sun as much as possible and that seems to help. Perhaps it is a sun sensitivity. I've had so many weird things happening to my body lately. I'll just add this to the growing list...sigh...