What is body temperature?

Body temperature is a measure of how well your body can make and get rid of heat. The body is very good at keeping its temperature within a safe range, even when temperatures outside the body change a lot.

• When you are too hot, the blood vessels in your skin widen to carry the excess heat to your skin's surface. You may start to sweat. As the sweat evaporates, it helps cool your body.
• When you are too cold, your blood vessels narrow. This reduces blood flow to your skin to save body heat. You may start to shiver. When the muscles tremble this way, it helps to make more heat.

Your body temperature can be measured in many places on your body. The most common ones are the mouth, the ear, the armpit, and the rectum. Temperature can also be measured on your forehead.

Thermometers show body temperature in either degrees Fahrenheit (°F) or degrees Celsius (°C). In the United States, temperatures are often measured in degrees Fahrenheit. The standard in most other countries is degrees Celsius.

A normal body temperature is about 98.6ºF. Some people have a normal temperature that is a little higher or a little lower than this.

Your temperature may be a little lower in the morning than it is later in the day. It may go up during hot weather or when you exercise, wear heavy clothes, or take a hot bath.

Your temperature may also be different depending on how you take it. A temperature taken in the mouth (oral) or under the arm may be a little lower than your core temperature (rectal).