Hot Yoga studios typically heat the room to the temperature of 35–42 °C , with a humidity of at least 40%.
When I was younger, I was able to adjust to the heat and continually go to a studio to practice. Ever since I started getting chronic migraines two years ago, I have been unable to go to a Bikram class because the room temperature gives me a migraine straight away.
So, I decided to sort of make my own Hot Yoga room. I bought a Heating fan with ceramic heating element 1200/2000 W, a temperature and humidity thermostat, and a humidifier that allows for the option of warm or cold mist.
I normally practice yoga in my office at home which is a pretty small room. It doesn't take a lot of energy to heat up, and it gets to high temperatures. Hot enough for me anyway. I also roll up a towel and put in the crack of the door to capture all the heat.