It's hot out here in Idaho. Sometimes in the upper 90's and humid, holy crap. It's not easy training in that kind of heat no matter how many fans on in the house. Being in the Dungeon is no picnic either and end up most of the time doing playouts in my boxers only. One of the things that help on occasions is only doing a small bit of training than go on to do something later in the day. It gets so hot at times I barely want to eat and maybe a few exercises just to let myself know I have done something.
Usually regardless of the weather lately I still manage to do 500 Hindu Squats and do a workout either right after or later on or even do a little something at night when it's cooler. Drinking water is basically a necessity and refilling practically every time. If you're an athlete, 2 gallons of water a day might be your best option. I do my best to try to drink a gallon a day but even that is a challenge because heat can do crazy things to you; lose appetite at times, tired & other sorts. It's not fun when it's so hot you barely want to do anything and it can be even more challenging when you have trouble sleeping.
I build up heat very easily so one of the things I manage to keep consistent is taking cold showers a little more frequently sometimes up to 4x a day because if I overheat and no matter how much water I drink if I don't stay cool enough there's a possibility of heatstroke. Heatstroke is no joke and people can die from it of neglecting to keep their body at level temperature and drinking enough water. Cold Showers are a must in my opinion. You may hate it at first but if you're only taking hot showers it's practically redundant and not letting your body be at a level of temperature it needs to maintain energy. Some people can handle heat like nobody's business but regardless even for them there's a limit. Heat can be life giving but if it's past a certain limit it can also be damaging so it's important to maintain balance for your body.
If you plan on taking on the heat, be safe and keep cool as best as possible.