What is the Average human body temperature in degrees Celsius?

The average normal human body temperature is 37 degrees C (98.6 degress F) but it can vary somewhat for an individual.
The average adult temperature is 36.8 degrees C (98.2 degrees F). Older people will average a bit less. These values can also vary with time of day, with a typical individual range of 0.5 degrees C (0.9 degrees F)
Temperatures can and will be markedly different with exposure to cold or hot environmental temperatures.

According to Mosby's Canadian Textbook for the Support Worker:
Average Human Temp;:
Oral (mouth) - 37 c (98.6 f)
Tympanic (ear) - 37.4 c (99.3 f)
Axillary (underarm) - 36.5 c (97.8 f)