Women's hormones change so significantly during the course of their cycles that just by looking at graphs of daily temperatures you can see when ovulation occurs, if implantation has taken place, or when the period is about to start. It can even spot subtle signs of hormone imbalance, for example, if enough there's not enough progesterone being produced to sustain pregnancy.

Not just any temperature though, specifically our basal body temperature (BBT) is what must be measured to better understand what our hormones are doing. Basal refers to the bottom, in this case it's the lowest our temperature gets each day. For most people, that happens to be when you first wake up in the morning, after your body and metabolism have been resting several hours.

I wrote earlier about the Fertility Awareness Method (FAM,) which uses temperature charting as a major component of tracking the menstrual cycle and determining a woman's fertile window. Click the link above to learn more about FAM and if it's right for you.