The body temperature under the tongue during ovulation is approximately between 36.7-37.0°C. A woman’s basal body temperature usually changes with ovulation. The basal body temperature decreases suddenly on the day of ovulation and gradually increases after the day of ovulation, remaining until the temperature drops again at the onset of menstruation. Normal conditions are represented by the sublingual, rectal and axillary body temperatures, with the rectal temperature being the closest to the deep body temperature. The normal value of sublingual temperature is 36.3-37.0°C. The normal value of rectal temperature is 36.5 to 37.0°C, which is 0.2-0.5°C higher than the oral body temperature. The normal value of axillary temperature is 36.0-37.0°C, and the sublingual temperature is closer to the body temperature. However, be careful not to drink hot or cold water before taking the temperature, so as not to affect the results of the measurement.