I'm new to POTS (or at least newly diagnosed), but living in South Alabama, where we saw 90+ in April, I know heat. Simple stuff can really help a lot- make sure you wear breathable fabrics, keep your hair off your neck, keep drinking cool drinks, stay in the shade when possible. Also, try to stay in well ventilated areas. You might want to get a little personal fan- they make great ones that attach to water bottles so you can mist off. Jump in the pool when you can. One thing- although it might be tempting to dash into a super-cool place or drink a big glass of ice water, it's always best to try to avoid drastic temp. changes. I know it makes me feel like crap when I go from hot to cold too fast. So, if you get too hot, drink a glass of luke-warm water first, then a glass of ice water. Same thing with the shower. Walk slowly into cool buildings, spending a few minutes by the door first to let your body get adjusted. Good luck!