Temperature gives an indication of core body temperature. Body temperature can be an indication of a fever (temp > 38.5 °C/101.3 °F) or hypothermia. Use a thermometer to measure the temperature in the mouth (oral) is about 36.8 °C (98.2 °F)
A study from Small and Clements suggests 37.5 as a cutoff.
The following thermometer readings generally indicate a fever:
Rectal, ear or temporal artery temperature of 100.4 (38 C) or higher
Oral temperature of 100 F (37.8 C) or higher
Armpit temperature of 99 F (37.2 C) or higher