Coldness is one of the six external pathogens that is prevalent in the winter season.  Attack of the exterior occurs when the body is not properly protected against cold temperature.  It can also occur directly to the interior of the body when there is over-consumption of cold drinks.

Summer Heat, as the name implies, is an external pathogen that exists only during summer, and therefore the resulting illnesses only occur in that season.

Summer Heat is a Yang pathogen that results from an over abundance of Yang. The resulting symptoms of such an attack manifest as excessiveness of Heat, such as fever, flushed face, heavy pulse, dry mouth and dysphoria.

The upward bearing and dispersing nature of Summer Heat lead to profuse sweating.  At the same time, the excessive Yang from Summer Heat also consumes the Yin Fluids in the body, causing deficiency in Body Fluids, while leading to loss of Qi.  Together, the deficiency of Qi and Yin produce symptoms of extreme thirst, craving for cold drinks, concentrated and scanty urine or even heat stroke.

Dampness often accompanies Summer Heat due to the overconsumption of cold drinks and excessive rain.  

Wind attack.  The body is susceptible when it just recovered from trauma, such as child birth or major surgery, or major illness.