What is the normal human body temperature?

Extracted from Singapore Science Centre…

“Normal” body temperature depends on when, where, and in whom it is measured. Body temperature fluctuates about 1 degree Celsius in a 24-hour cycle. It tends to be lowest in the early morning and highest in the late afternoon. Temperature also varies from one place in the body to another.

The most important body temperature is the core temperature — the temperature of organs in the cranial, thoracic, and abdominal cavities. Rectal temperature is relatively easy to measure and gives an estimate of core temperature: usually 37.2 to 37.6 degrees Celsius. It may be as high as 38.5 degrees Celsius in active children and some adults. Women experience a monthly rhythm in core temperature in connection with their menstrual cycle. The core temperature averages 0.5 degree Celsius higher during the last half of the cycle from the time of ovulation to menstruation.

Shell temperature is the temperature closer to the surface, especially skin and oral temperature. Here, heat is lost from the body and temperatures are slightly lower than rectal temperature. Adult oral temperature is typically 36.6 to 37.0 degrees Celsius but may be as high as 40 degrees Celsius during hard exercise.