The core temperature of the average human is 98.6 F or 36.9 C. Some people are naturally lower while others are higher. A deviation from this average temperature indicates a problem. Our bodies work at their best when we maintain this optimal core temperature. If the body is too cold, the organs will start to suffer hypothermia and begin to shut down. If the body is too hot, the brain and organs will also begin to suffer. When a person has a mild to moderate fever, it usually indicated the body is fighting of an infection or virus. The increased temperature helps to kill the foreign germs. If the fever becomes too high, it is important to cool the body down to prevent damage.