normal body temperature
Refers to a person's usual, healthy body temperature, often around 36–37°C. Commonly used in medical or daily health contexts.
My normal body temperature is 36.5 degrees.
朝起きたらまず平熱を測ります。
I measure my normal temperature first thing in the morning.
平熱 is one's normal body temperature, the opposite state of having 熱 (a fever).
Compound of 平 (flat, normal) and 熱 (heat, fever). The term is straightforward and transparent, referring to one's normal body temperature.