Evaporation of water from your skin if it is wet
(sweating). If your clothing is wet, you will also lose some body heat through
evaporation and through respiration (breathing) when the body temperature is
higher than 99°F (37°C). During
intense exercise, the body loses 85% of its heat through sweating.
to heat leaving a woodstove). This normal process of heat moving away from the
body usually occurs in air temperatures lower than
68°F (20°C). The body loses 65%
of its heat through radiation.
Conduction (such as heat loss from
sleeping on the cold ground). Heat is lost in air temperatures lower than
68°F (20°C). The body loses
about 2% of its heat through air conduction. However, water causes more heat
loss from the body than air does, so heat can be lost from the body very
quickly when it is placed in cold water.
Convection (similar to
sitting in front of a fan or having the wind blow on you). The body loses 10%
to 15% of its heat through convection.
Heat loss through evaporation and respiration increases in dry, windy
Wet clothing greatly increases heat loss through conduction and
Heat loss in cold, wet weather increases the risk for
hypothermia and cold injury. Heat loss can occur in
warm temperatures through conduction. Swimming or sitting in cool or cold water
can cause the body to lose heat very quickly and increase the risk for
Hypothermia can occur quickly (within a few hours) or gradually over
days and weeks depending on a person's age, overall health, and environmental
How this information was developed to help you make better health decisions.