The normal temperature of human blood is roughly 98.6 degrees Fahrenheit, also known as "blood heat." This is also the normal body temperature for humans, although the temperature fluctuates by as much as one degree throughout the day. Blood gets closer to the skin to shunt excess heat, and blood vessels constrict to draw more body heat inward when the body gets too cold.
Muscle activity generates more heat in the body and keeps the body warm. This is why humans involuntarily shiver. This may also explain the phrase "get the blood pumping" to increase body heat.
Body temperature, and therefore blood temperature, can be measured many ways. The most common method is through the mouth or armpit. Temperature can also be measured on the ear, forehead or in the rectum.
When blood is stored after someone donates a pint of blood at a blood collection center, it is kept at a temperature of 6 degrees Celsius, or 42.8 degrees Fahrenheit, for up to 42 days in cold storage until the blood is needed. Blood platelets are stored at room temperature in agitators for up to five days. Blood plasma and cryoprecipitate are frozen and stored for up to one year.