The average normal body temperature is 98.6 degrees Fahrenheit, but it may vary by up to 1 degree Fahrenheit higher or lower from person to person, according to WebMD. Individual body temperature may also vary by up to 1 degree Fahrenheit over the course of a day.
Body temperature can be affected by time of day and level of activity, says WebMD. Hormone levels can also affect body temperature, so women's body temperatures fluctuate during both ovulation and menstrual periods.
The most common places to measure body temperature are the mouth, ear, armpit and rectum. Rectal temperatures are the most accurate way to measure body temperature and are slightly higher than a temperature taken orally, according to WebMD.