I have travelled a few times to hot & humid countries and always develop red blotches on the lower legs. They become very hot and it feels like they are burning from the inside. In extreme cases I have needed to apply cold gel packs to enable me to sleep comfortably. I always wear long pants or ankle length skirts, so my legs do not get sun burnt. The blotches are not raised at all, and tend to disappear within a couple of weeks of returning home.
I would like to know what causes it and how to treat it. I don't seem to get the same reaction when travelling to colder climates. I have posted a photo on my profile page.