Cold is the most common way an ordinary outdoor day turns dangerous. Hypothermia does not need a blizzard: the CDC says it strikes during very cold weather or when people are chilled from rain, sweat or cold water. Because it affects the brain, a person may not realize it is happening. That is why cold-weather survival is about prevention and spotting signs early, in yourself and your partners.
How hypothermia happens
When exposed to cold, your body loses heat faster than it produces it. Prolonged exposure uses up stored energy, and body temperature drops. NIOSH notes that low body temperature affects the brain, making a person unable to think clearly or move well.
Early and late warning signs
The CDC lists shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness as signs of hypothermia. Seek immediate medical attention when you see them.
- Early: shivering, fatigue, loss of coordination, confusion and disorientation.
- Late: no shivering, blue skin, dilated pupils, slowed pulse and breathing, loss of consciousness.
Stay warm and dry
Insulation, meaning extra layers, is one of the Ten Essentials, along with emergency shelter. Pack them even on short summer hikes.
Parks Canada's lost-child guidance applies to adults too: tuck in your shirt, tuck pant legs into socks and zip up your jacket to trap warmth. A nest of twigs and leaves at the base of a tree insulates you from the cold ground, which pulls heat away fast.
Mountain rescuers who teach the Hug-a-Tree program put it bluntly: hypothermia, not hunger or thirst, is what kills lost children. Shelter and staying dry come before finding food.
Quick answers
What are the first signs of hypothermia?
Shivering, fatigue, loss of coordination and confusion, according to CDC/NIOSH.
Can you get hypothermia when it is not freezing?
Yes. The CDC says it can strike when people are chilled from rain, sweat or cold water.
Is shelter or food more important in the cold?
Shelter and warmth. Search teams say hypothermia, not hunger or thirst, is the main danger to lost people.
General education, not medical advice or a substitute for training. In an emergency, call 911 or your local emergency number. Updated 2026-10-26.