Hypothermia doesn’t only happen on snowy mountaintops. Hikers, kayakers, and campers can develop it on a cool, wet, windy day in spring or autumn, especially when tired or soaked through. It creeps up gradually, and one of its most dangerous features is that it clouds judgment, so the person affected often doesn’t realize what’s happening. This guide explains how to recognize hypothermia, how to treat it safely in the outdoors, and how to prevent it.
What Is Hypothermia?
Hypothermia is a drop in core body temperature below about 95°F (35°C). Your body loses heat faster than it can produce it, and as your core cools, your heart, nervous system, and other organs stop working normally. It’s different from frostbite, which is localized freezing of skin and tissue, although the two can occur together.
What Causes Hypothermia Outdoors?
- Wet clothing: Water conducts heat away from the body many times faster than air. Rain, sweat, and river crossings are common culprits.
- Wind: Wind strips away the warm layer of air around your body.
- Cold water immersion: Falling into cold water, such as during a kayak capsize, cools the body very quickly.
- Exhaustion and poor nutrition: A tired, hungry body produces less heat.
- Alcohol: Alcohol widens blood vessels and increases heat loss while dulling awareness of the cold.
Warning Signs of Hypothermia
Mild Hypothermia
- Uncontrollable shivering.
- Cold, pale skin.
- Clumsiness and trouble with fine motor tasks like zipping a jacket.
- Mild confusion, poor decision-making, or apathy.
- Fast breathing.
A useful memory aid is the “umbles”: someone who stumbles, mumbles, fumbles, and grumbles may be developing hypothermia.
Moderate to Severe Hypothermia
- Shivering slows or stops (a dangerous sign, not an improvement).
- Slurred speech and severe confusion.
- Drowsiness, slow breathing, and a weak pulse.
- Loss of coordination and inability to walk.
- In severe cases, unconsciousness.
How to Treat Hypothermia: First Aid Steps
Step 1: Call for Help if Needed
If the person is confused, has stopped shivering, is drowsy, or is unconscious, call emergency services or activate a personal locator beacon immediately. Moderate and severe hypothermia need medical care.
Step 2: Get Out of the Cold
Move the person to shelter, such as a tent, a hut, or behind rocks out of the wind. If you can’t move them, shield them from wind and get them off cold ground with a sleeping pad, pack, or extra clothing.
Step 3: Handle Them Gently
Move the person carefully and avoid rough handling. In severe hypothermia, the heart becomes irritable, and jolts can trigger a dangerous heart rhythm.
Step 4: Replace Wet Clothing
Remove wet clothing and replace it with dry layers. If removing clothing would expose them to more cold, cut it away or place dry insulation and a waterproof layer over the wet clothes.
Step 5: Insulate and Rewarm Gradually
Wrap the person in a sleeping bag, blankets, or a “hypothermia wrap”: a sleeping bag inside a waterproof layer, with insulation underneath. Cover the head and neck. Warm water bottles or heat packs wrapped in cloth can be placed in the armpits, chest, and groin. Never put heat packs directly on the skin. Skin-to-skin contact with another person inside a sleeping bag can also help.
Step 6: Give Warm, Sweet Drinks
If the person is fully alert and able to swallow, give warm, sweet, non-alcoholic drinks and high-energy food. Sugar fuels shivering, which generates heat. Never give food or drinks to someone who is drowsy or unconscious.
Step 7: Monitor Breathing
Keep checking breathing and responsiveness. If the person stops breathing, begin CPR and continue until help arrives.
Hypothermia After Falling Into Cold Water
Cold water immersion is a special case worth understanding, especially for paddlers. In the first minute after falling into cold water, a “cold shock” response causes gasping and rapid breathing, which is the most dangerous stage because it can lead to inhaling water. Over the next few minutes, your muscles cool and lose strength, making swimming difficult. True hypothermia usually takes 30 minutes or more to develop, which is why a life jacket matters so much: it keeps you afloat while you control your breathing and get out.
If someone has been in cold water, get them out horizontally if possible, handle them gently, and follow the same rewarming steps above. Even if they seem fine, watch them closely for the next few hours. Practicing self-rescue, such as how to right a capsized kayak, shortens the time you spend in the water.
What to Carry in Your Pack
A small hypothermia kit adds very little weight: an emergency space blanket or bivy bag, a spare insulating layer, a warm hat and gloves, a lightweight stove or insulated flask for hot drinks, high-calorie snacks, and a way to call for help such as a charged phone or personal locator beacon.
What Not to Do
- Don’t rub or massage the arms and legs; this can push cold blood toward the heart.
- Don’t use hot water, heating pads, or fires directly on the person; this can burn numb skin.
- Don’t give alcohol or caffeine.
- Don’t let someone with moderate hypothermia walk or exert themselves.
How to Prevent Hypothermia While Hiking and Paddling
- Dress in layers. Use a moisture-wicking base layer, an insulating mid-layer, and a waterproof, windproof shell. Our guide to what to wear hiking covers layering in detail.
- Avoid cotton. Cotton holds moisture and loses its insulating value when wet.
- Stay dry. Put on rain gear early and vent layers before you start sweating heavily.
- Pack extra layers. Always carry a spare warm layer, hat, and gloves, even on short day hikes.
- Eat and drink regularly. Snacks fuel your body’s heat production.
- Dress for the water. Kayakers should dress for the water temperature, not the air, and wear a properly fitted life jacket.
- Watch your group. Look out for the “umbles” in your companions, since people often can’t recognize hypothermia in themselves.
- Turn back early. If the weather deteriorates, don’t push on.
Frequently Asked Questions
What is the first thing to do for hypothermia?
Get the person out of the cold and wind, call for help if symptoms are moderate or severe, and replace wet clothing with dry insulation.
Can you get hypothermia in summer?
Yes. Hypothermia can happen in temperatures well above freezing if you’re wet, exposed to wind, or in cold water, especially in mountains and near lakes.
Why is it dangerous when shivering stops?
When shivering stops in a cold person, it often means hypothermia is getting worse and the body can no longer generate heat. It’s a sign that emergency help is needed.
Should you rub someone with hypothermia to warm them up?
No. Rubbing the limbs can push cold blood to the core and may trigger heart problems. Rewarm gently with insulation and warm packs on the torso.
How long does it take to recover from mild hypothermia?
Someone with mild hypothermia often recovers within a few hours once they are dry, insulated, fed, and warm, but they should be monitored and should not continue a strenuous hike that day.