The high temperature phase of ovulation lasts 12-14 days in a normal menstrual cycle. The basal body temperature is the first thing you do when you wake up in the morning. The basal body temperature is the first thing you do when you wake up in the morning, and the temperature taken at that time is called the basal body temperature. By monitoring the curve of the basal body temperature every day, you can monitor whether ovulation has occurred. After ovulation, the level of progesterone secreted in the body increases significantly, and the level of progesterone causes the body temperature to increase by 0.3 to 0.5 degrees Celsius. So after ovulation there is an increase in basal body temperature, and with the atrophy of the corpus luteum, the progesterone level decreases and the basal body temperature returns to normal. So the high-temperature phase of basal body temperature, which is the maintenance time of the luteal phase, is usually about 12-14 days.