There are a lot of fun points to cover here so I'm going to do this bullet point style Despite what all of our moms told us, 98.6 degrees is not your normal body temperature. This number arose about 150 years ago using a machine that took 20 minutes to take a temperature and understandably, our technology and data analyzing ability has improved by leaps and bounds since then. If your body is a car, which is always a great analogy, you know that it's going to be cool when you start driving it and warmer when you're done. Similarly, your temperature is higher at the end of the day than the beginning. A normal 6 am temperature is between 96.8-98.9 and a normal 6 pm temperature is 97-99.6 . Usually there's about a 1 degree difference over the course of the day for most people. These numbers are based on oral temperature measurements. Sadly for most of us, rectal measurements are about the most accurate as they represent closest to your body's core temp...
Scott Selinger, MD, FACP musing on the questions you keep meaning to ask your doctor