Mammals are warm-blooded. This means that the temperature inside their bodies stays about the same whatever the weather is like outside. Most mammals have a body temperature of about 36°C-39°C (97°F-102°F). Warm blood allows mammals to be very active and to live in a wide variety of places, from the icy Poles to the hot Tropics. Fur and fat help protect them from the cold and they get rid of excess heat by sweating or panting.