What is it called when it is cold outside and your body is able to maintain its temperature at approximately 98.9 this ability to maintain body temperature is called?

The ability of the body to maintain its internal temperature around 98.6°F (37°C) despite external cold conditions is called thermoregulation. This process involves various physiological mechanisms, such as shivering, vasoconstriction, and hormonal adjustments, to preserve heat and maintain homeostasis.