Re lymphoedema, my therapist is clear that having my arm in warm/hot water for any length of time is not a good idea. I am therefore noticeable at spas as the woman who is apparently wanting to leave the room, with my left arm raised above the water line!! Same with air temperature - current weather in Melbourne will have little effect on my arm, above 26 or so encourages fluid to hang around. One of the problems people encounter in humid climes is trying to get a compression garment on over a sticky warm body part, but unfortunately that's the time you need it most.