Hypothermia is a medical condition in which the internal temperature of a living organism drops below that which is required for normal metabolism and bodily function.
In 2151, Commander Charles Tucker III and Lieutenant Malcolm Reed of the starship Enterprise NX-01 suffered hypothermia during a mission aboard the Enterprise's Shuttlepod 1 when the shuttle became low on oxygen and power. (ENT: "Shuttlepod One")
In 2266, a USS Enterprise landing party led by Hikaru Sulu suffered hypothermia and frostbite on the planet Alfa 177 when they were stranded on the planet's surface during the night as temperatures fell to 75 degrees below zero. (TOS: "The Enemy Within")