The average normal body temperature of a human is 98.6 degrees Fahrenheit when measured by mouth, although some newer studies show it to be closer to 98.2. Normal temperatures, however, vary among individuals and may change throughout the course of the day.
So-called normal temperatures range from 97 to 99 degrees but can even vary from that span and be considered harmless. Activity and exposure to extreme outside temperatures can alter the body temperature.
Age also plays a factor. The temperature of older adults tends to be slightly lower. A person with a temperature exceeding 100.4 generally is classified as having a fever due to illness. Hypothermia, which is quite dangerous, occurs when the body temperature drops to below 95 degrees.