Hypothermia happens when the body loses heat faster than it can produce heat and the body temperature falls below 95 degrees Fahrenheit (35 degrees Celsius). Left untreated, it can be life-threatening.
Hypothermia is often caused by exposure to cold weather or immersion in cold water. Ongoing exposure to cool indoor temperatures also can cause hypothermia, especially in older adults and babies. Being exhausted or dehydrated increases the risk of hypothermia.