Hypothermia Symptoms: The Three Stages, Warning Signs, and What to Do

Hypothermia sets in when body core temperature falls below 95 degrees Fahrenheit. It is the medical emergency that gets confused with “just being cold.” It can develop in temperatures up to 50 degrees if a person is wet or exhausted, and it kills about 1,300 Americans a year per CDC data. Below are the three stages, the symptoms at each, what to do, and the situations where the risk is highest. Consult a medical professional for treatment; the information below is for recognition.

Stage 1: Mild Hypothermia (90 to 95 Degrees)

Body core temperature 90 to 95 degrees Fahrenheit (32 to 35 degrees Celsius). The body is still trying to warm itself.

Symptoms: Strong, persistent shivering. Slurred or slow speech. Increased heart rate. Fast breathing. Fatigue, drowsiness. Pale skin, cold to the touch. Mild confusion or impaired judgment. Difficulty with fine motor tasks (zippers, gloves).

The “umbles.” Wilderness medicine taught the early-warning rule: stumbles, mumbles, fumbles, grumbles. If a hiker, hunter, or outdoor worker starts walking unsteadily, slurring, dropping things, or getting irritable, they are already in mild hypothermia.

What to do. Move them to warm shelter. Strip wet clothing. Replace with dry layers and blankets. Skin-to-skin contact helps for severe wet exposure. Warm sweet drinks (no alcohol, no caffeine). They can usually rewarm safely with these steps. Stay with them until shivering stops and speech is clear.

Stage 2: Moderate Hypothermia (82 to 90 Degrees)

Body core temperature 82 to 90 degrees Fahrenheit (28 to 32 degrees Celsius). The body’s compensation mechanisms are failing.

Symptoms: Violent shivering that then stops abruptly (a critical warning sign). Severe confusion, slurred speech, may not recognize family. Increasing drowsiness, may seem to want to sleep. Slow, weak pulse. Slow shallow breathing. Blue or gray lips, fingers, and toes. Loss of coordination and inability to walk steadily.

What to do. Call 911. Move gently to shelter (rough handling can trigger cardiac arrhythmia). Begin gradual rewarming: dry clothes or blankets, warm packs to neck, chest, and groin only (not extremities). Skin-to-skin contact under shared blankets if no medical care is available within an hour. Do not rub limbs. Do not put a moderately hypothermic person in a hot bath; rapid rewarming of cold blood from the extremities can cause cardiac collapse, called afterdrop.

Stage 3: Severe Hypothermia (Below 82 Degrees)

Body core temperature below 82 degrees Fahrenheit (28 degrees Celsius). Life-threatening medical emergency.

Symptoms: Unconsciousness or unresponsive to stimulation. Stiff muscles. Faint, slow, or undetectable pulse. Breathing slow, shallow, or apparently absent. Pupils dilated. Skin cold and pale, may appear blue. The person may appear dead but is not necessarily; standard medical guidance is “no one is dead until warm and dead.”

Paradoxical undressing. Roughly 20 to 50 percent of fatal hypothermia cases involve victims removing clothing in the late stages. The mechanism is not fully understood but appears to involve constricted blood vessels suddenly dilating, creating a misleading sensation of heat. Encountering a hypothermia victim partially undressed in cold weather is a sign of severe hypothermia, not assault or suicide.

What to do. Call 911 immediately. Handle very gently; rough movement can trigger cardiac arrest. Do not start CPR unless the person is clearly not breathing and there is no detectable pulse for at least 60 seconds (severe hypothermia slows the pulse to nearly imperceptible). If trained and necessary, begin CPR and continue until medical help arrives. Active rewarming in this stage requires hospital equipment.

Who Is Most at Risk

Elderly. Lower metabolic rate, thinner skin, often medications that affect circulation. Hypothermia can develop indoors at 60 to 65 degrees in older adults.

Infants and young children. Higher surface-area-to-mass ratio, less ability to shiver effectively.

People who have been drinking. Alcohol dilates skin blood vessels, increasing heat loss. It also impairs judgment about cold danger.

Outdoor workers, hikers, hunters, ice fishermen. Wet from snow, sweat, or water. Wind compounds heat loss dramatically.

Homeless populations. Persistent exposure with no recovery time.

People with certain medical conditions. Hypothyroidism, diabetes, sepsis, severe malnutrition.

Wet, Wind, and the 50-Degree Threshold

Hypothermia is not a “below freezing” problem only. It can develop in temperatures up to 50 degrees Fahrenheit if any of three conditions apply:

Wet. Wet clothing loses heat 25 times faster than dry. A backpacker caught in a 45-degree rain is at higher risk than a hiker in 25-degree dry air.

Wind. Wind chill strips heat from skin and clothing. NWS publishes wind-chill charts; at 30 degrees with 30 mph wind, frostbite can occur in 30 minutes.

Exhaustion. Spent muscles cannot generate heat through shivering. A long hike in cool damp weather kills more people than a single freezing night with proper gear.

For broader context on the cold weather events that increase hypothermia risk, see our piece on the polar vortex.

Prevention

Layer. Base wicking layer (wool or synthetic, never cotton against skin), insulating mid-layer, weatherproof outer shell.

Stay dry. Change out of wet clothes immediately. If you fall in water, the first priority is to get dry, even before warmth.

Protect head, hands, feet. The body loses 7 to 10 percent of total heat through the head. Hats matter more than people think.

Eat and drink. Bodies need fuel to make heat. Carbohydrates and warm fluids both help.

Travel with someone. Hypothermia impairs judgment about hypothermia. A buddy can spot the umbles before you do.

Frequently Asked Questions

What temperature is hypothermia?

Hypothermia begins when body core temperature falls below 95 degrees Fahrenheit (35 degrees Celsius). Mild hypothermia is 90 to 95 degrees. Moderate is 82 to 90 degrees. Severe is below 82 degrees.

What are the early signs of hypothermia?

Strong shivering, slurred speech, slow movement, fumbling fingers, mild confusion, fatigue. Wilderness medicine teaches the “umbles” rule: stumbles, mumbles, fumbles, grumbles. Any of these in cold conditions warrant immediate warm shelter and dry clothing.

Can you get hypothermia in 50 degree weather?

Yes, if you are wet, windy, or exhausted. Wet clothing loses heat 25 times faster than dry, so a 45 degree rainstorm or a fall into cold water can produce hypothermia faster than a dry 20 degree day.

What does paradoxical undressing mean?

In late-stage severe hypothermia, victims sometimes remove clothing because constricted blood vessels suddenly dilate and create a false sensation of heat. It happens in roughly 20 to 50 percent of fatal cases. A hypothermia victim partially undressed in cold weather is severely hypothermic, not behaving rationally.

Should you give a hypothermia victim a hot bath?

Mild hypothermia, yes; moderate or severe, no. Rapid rewarming of cold blood from the extremities can cause cardiac collapse called afterdrop. Moderate and severe hypothermia need gentle rewarming with dry clothes, warm packs to the core only, and medical care.

When should I call 911 for hypothermia?

Anytime you suspect moderate or severe hypothermia (severe confusion, blue lips, weak pulse, unconsciousness). For mild hypothermia, call if symptoms do not improve within 30 minutes of warm shelter. When in doubt, call. Hypothermia can deteriorate fast.