Hypothermia 101

Last updated: August 1, 2026. Cold injury guidance is safety-critical. Use current medical and emergency guidance, and call 911 or local emergency services for serious symptoms.

Hypothermia is a condition that occurs when inner body temperature drops more than two degrees below normal. It means the body is seriously cold and losing heat faster than it can produce it. The body loses body heat four ways: conduction, convection, radiation and evaporation.

When people begin to lose heat from exposure, they will shiver and exercise to stay warm. These actions drain energy and slowly lead to exhaustion. The body’s energy reserves will be depleted and the body core temperature will drop further. If untreated, exposure leads to hypothermia, the number one killer of those who participate in outdoor activities.

You Have Three Defences Against Hypothermia

Wear proper layered clothing. Stay dry. Wet clothing loses most of its insulating value. Wool clothing is able to retain more of its insulating properties when wet.
Get out of the elements. If you cannot stay dry and warm under existing weather conditions, get out of the wind and rain. Build a fire, construct a shelter, or make camp before you are tired.
Detect hypothermia. Symptoms of hypothermia can be difficult to detect, or even to be aware of. Watch for the symptoms below.

Stages Of Hypothermia

Mild: feeling cold, shivering and may be uncoordinated.
Moderate: intense shivering, obvious lack of coordination, possible confusion, otherwise known as the “umbles” such as stumbles and mumbles.
Severe: shivering may stop, coordination may become very poor and confusion can increase. Severe hypothermia may lead to semi-consciousness or unconsciousness, erratic respiration and heartbeat.

First Aid For Mild Or Moderate Hypothermia

Remove any wet clothing and get dry.
Get warm by wrapping in blankets, putting on dry clothing and moving to a warm place.
Apply available heat sources, such as a hot water bottle or heating pad.
Get warm liquids into the person if they are alert and able to drink safely.
Do not rewarm too quickly.

If Someone Is In A Severe State Of Hypothermia

Do not attempt to rewarm aggressively. Do not rub or massage the victim’s skin. Warming can cause cold blood from the extremities to return to the core of the body, further lowering body-core temperature, which may lead to death.
Place the victim in dry clothes, blankets or a sleeping bag to prevent further heat loss.
Do not permit the victim to walk. Transport to a medical facility immediately. Advanced hypothermia requires special rewarming methods.

Original Sources

Atlantic Provinces Hunter Education manual.
Original post also referenced johnnygeo-blog.blogspot.com hypothermia guest article notes.
Original post also referenced hypothermia.org on-land guidance.