Not Medical Advice: You need to wait for 15-20 minutes after eating or drinking, exercising, taking a shower, or smoking before taking your temperature. But if it’s after taking a hot bath, you need to wait for one hour.
Normal body temperature varies by age, activity, and time of day. It is generally accepted as 98.6°F (37°C) throughout the day, usually being lowest in the early morning and rising as much as 1°F (0.6°C) in the early evening. Temperature may also increase by 1°F (0.6°C) or more if you exercise on a hot day.
A woman's body temperature usually varies by 1°F (0.6°C) or more through her menstrual cycle, peaking around the time of ovulation.
Subzero temperatures can do a number on your body in short order. According to experts, a wind chill of -50°F (-45°C) can cause frostbite in five minutes. Find out more at National Geographic.