Because when you take a bath with cold water, cold water will lower your body temperature for a short time and increase the speed of heat production. It is cold when washing, but after washing, the body heat is not released in time, but it will feel hot.
On the contrary, using hot water will slow down the generation of body heat, and sweating will also bring out body heat when washing. Although it feels very hot when washing, it will be very cold after washing.
So taking a hot bath in summer is better than taking a cold bath in terms of relaxation and freedom.
However, ease and freedom belong to ease and freedom. If the conditions don't allow, it's better to use cold water, because it's very water-saving and refreshing, but forget the bad nerves and don't insist.