Hypothermia and hyperthermia are frequent causes of death by law and high temperatures, the ones out body cannot protect from and fight with. The limits of our body start and finish at certain levels. Hot Air Normal body temperature is generally considered to be 98.6 ° F (37 ° C) orally and approximately 1 ° F (0.6 ° C) higher rectally. Body temperature can vary from individual to individual, by age, time of day or physical exertion. Thus, newborns and the elderly have temperatures averaging 1 ° C higher. Cyclic changes in body temperature occur with decreases of 0.5 ° C early in the morning (approximately 1:00 to 2:00 a.m.) and slight elevations later in the morning and afternoon. Hard exercise can raise the rectal temperature up to 104 ° F. Rectal temperatures of 39–40 ° C are common in marathoners after a race. Maintenance of normal body temperature is a delicate balance between heat load and heat loss. Heat load is the sum of heat generated by oxidation of ...