Over time, the human body adjusts to differences in temperature. For instance, when I was in southern Vietnam where the temperature and humidity were both around 90, the people were more comfortable outside than in air conditioning. I stayed inside as much as possible.
Of course appropriate clothing and shelter also help people live comfortably in extreme temperatures. Many cultures also observe a siesta in the heat of the day and work when the temperatures are relatively cooler.
How do some people manage to live comfortably in extremely hot or cold climates?
2 answers
One such area with very hot climate is india, and people there are used to this type of climate. People who live there wear light suits, and usually are always outside. The main point is that people just get "used" to the area they're living in. For some people it can take around 3 years to get used to their climate. It's not so bad living in a area that is cold, when you have heat and a blanket.