Fever is indicated when human body temperature rises about one degree or more over the normal temperature of 370 degrees celsius 986 degrees fahrenheit. It can also monitor whether or not treatment is working. It is generally medically accepted that normal body temperature ranges between 365c 977f to 375c 995f. A high temperature is a fever. Until recently direct measurement of core body temperature required surgical insertion of a probe so a variety of indirect methods have commonly been used. The measurement of body temperature can help detect illness.
As per healthline low grade fever is during the period when an adults body temperature rises to 1004 f 38 c or a bit lower. A high grade fever is when the fever rises to 103 f 394. The normal body temperature for an adult is around 986f 37c but every persons baseline body temperature is slightly different and may consistently be a little higher or lower. However this is only possible up to a certain body mass and this type of measurement also takes a long time. Ear temperature measurement may be acceptable for observing trends in body temperature but is less useful in consistently identifying fevers. In adult patients the temperature of an axillary measurement is lower than a rectal measurement up to 19 c.
The normal axillary temperature range is approximately between 347 c and 373 c.