What is hypothermia?

what are some of the symptoms one may experience?

When the body is exposed to colder temperatures, however, its internal mechanisms may be unable to replenish the heat that is being lost to the body's surroundings.
Scary because, you suddenly feel strangely warm when you should be cold, although this has to be pretty extreme, a less extreme symptom would be the inability to stop shivering.

Hypothermia refers to any condition in which the temperature of a body drops below the level required for normal metabolism and/or bodily function to take place. In warm-blooded animals, core body temperature is maintained at or near a constant level through biologic homeostasis. When the body is exposed to colder temperatures, however, its internal mechanisms may be unable to replenish the heat that is being lost to the body's surroundings.
Stage 1
Body temperature drops by 1掳C - 2掳C below normal temperature C (1.8掳-3.6掳F, or between 96.8掳F - 95掳F). Mild to strong shivering occurs. Unable to perform complex tasks with the hands; the hands become numb. Blood vessels in the outer extremities contract, lessening heat loss to the outside air. Breathing becomes quick and shallow. Goose bumps form, raising body hair on end in an attempt to create a insulating layer of air around the body (a vestigial response, but useful in other species).
Stage 2
Body temperature drops by 2掳C - 4掳C (3.6掳F - 7.2掳F, or between 95掳F - 91.4掳F). Shivering becomes more violent. Muscle miscoordination becomes apparent. Movements are slow and labored, accompanied by a stumbling pace and mild confusion, although the victim may appear alert. Surface blood vessels contract further as the body focuses its remaining resources on keeping the vital organs warm. Victim becomes pale. Lips, ears, fingers and toes may become blue.
Stage 3
Body temperature drops below approximately 32掳C or 90掳F (normal is 37掳C or 98.6掳F). Shivering usually stops below 32掳C; difficulty speaking, sluggish thinking, and amnesia start to appear; inability to use hands and stumbling are also usually present. Cellular metabolic processes shut down. Below 86掳F (30掳C) the exposed skin becomes blue and puffy, muscle coordination very poor, walking nearly impossible, and the victim exhibits incoherent/irrational behavior including terminal burrowing behavior or even a stupor. Pulse and respiration rates decrease significantly but fast heart rates (ventricular tachycardia, atrial fibrillation) can occur. Major organs fail. Clinical death occurs. Because of decreased cellular activity in stage 3 hypothermia, the body will actually take longer to undergo brain death