Hypothermia and Frostbite: Warning Signs, First Aid and How City Residents Stay Safe in Extreme Cold

Quick answer: hypothermia is a dangerously low body temperature, below 95°F according to the CDC. Warning signs in adults include shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness; babies may have bright red, cold skin and very low energy. Frostbite usually starts with redness or pain, then white or grayish-yellow skin that feels firm, waxy or numb. Get the person somewhere warm, remove wet clothing, warm the center of the body first for hypothermia, use warm (not hot) water for frostbite, never rub frostbitten skin, and get medical care. If someone’s temperature is below 95°F, it is an emergency: call 911.

Extreme cold does not only threaten hikers and skiers. In cities, cold injuries happen on long walks home when transit stops, in apartments that lose heat during an outage, at bus stops in a strong wind and during ordinary errands for people who are older, ill or underdressed.

The good news is that both hypothermia and frostbite are largely preventable, and early first aid makes a real difference. This guide covers how to spot them, what to do and how to plan for cold snaps. It is part of our severe weather preparedness guide, which covers winter storms, heat, floods and hurricanes.

Sources: Centers for Disease Control and Prevention, “Winter Weather: Hypothermia,” “Winter Weather: Frostbite” and “Stay Safe During Extreme Cold”; National Weather Service, Wind Chill Chart and winter hazard products, including the Cold Weather Advisory and Extreme Cold Warning; Ready.gov, “Winter Weather”; National Institute on Aging, “Cold Weather Safety for Older Adults”; American Red Cross, winter storm safety. General safety information only. Call 911 for medical emergencies. Checked October 2026.

What Hypothermia Is

The CDC defines hypothermia as abnormally low body temperature, below 95°F. When the body loses heat faster than it can produce it, the brain is affected early, which is what makes hypothermia so dangerous: the person may not realize anything is wrong and may be unable to help themselves.

It does not require freezing weather. The CDC notes that hypothermia can occur even at cool temperatures above 40°F if a person becomes chilled from rain, sweat or immersion in cold water. Wet clothing, wind and exhaustion all speed up heat loss.

Warning signs

The CDC lists these signs:

Adults	Infants
Shivering	Bright red, cold skin
Exhaustion or feeling very tired	Very low energy
Confusion
Fumbling hands
Memory loss
Slurred speech
Drowsiness

Shivering can stop as hypothermia gets worse. A person who was shivering and then stops, while still cold and confused, is getting worse, not better.

Who Is Most at Risk

The CDC and the National Institute on Aging identify groups that face higher risk:

• Older adults, especially those with limited food, clothing or heating. The NIA notes that older bodies lose heat faster and that some medications and conditions make it harder to sense cold.
• Babies sleeping in cold rooms, since infants lose heat quickly.
• People who spend long periods outdoors, including people experiencing homelessness, outdoor workers and stranded travelers.
• People who have been drinking alcohol or using drugs, which can impair judgment and increase heat loss.
• People with certain health conditions, such as diabetes, thyroid problems or conditions that affect circulation or movement.

In apartment buildings, that list includes neighbors who live alone. During a heat outage or a severe cold snap, a quick knock on a door can catch a problem early.

First Aid for Hypothermia

If you notice signs of hypothermia, the CDC advises taking the person’s temperature if possible. A temperature below 95°F is an emergency; call 911.

While you wait for help, or if medical care is not immediately available, the CDC recommends:

1. Get the person into a warm room or shelter.
2. Remove any wet clothing.
3. Warm the center of the body first, meaning the chest, neck, head and groin. Use an electric blanket if available. Skin-to-skin contact under loose, dry layers of blankets, clothing, towels or sheets also works.
4. Give warm beverages if the person is alert and able to swallow. Avoid alcohol, which speeds heat loss.
5. Keep them dry and wrapped in a warm blanket, including the head and neck, once their body temperature has increased.
6. Get medical attention as soon as possible.

Handle the person gently. A person with severe hypothermia may appear to have no pulse or breathing. The CDC advises giving CPR if needed while the person is being warmed, and continuing until they respond or medical help arrives. Some people who appear dead can be resuscitated.

What not to do

• Do not warm arms and legs first. Warming the core is the priority.
• Do not put them in a hot bath or use very hot water.
• Do not give alcohol.
• Do not leave them alone while they are confused.

What Frostbite Is

Frostbite is an injury caused by freezing. It most often affects the nose, ears, cheeks, chin, fingers and toes, according to the CDC, and it can permanently damage the body. Severe cases can lead to amputation.

Warning signs

The CDC describes the first signs as redness or pain in any skin area. Other signs include:

• White or grayish-yellow skin
• Skin that feels unusually firm or waxy
• Numbness

Numbness is the tricky part. A person often does not realize they have frostbite because the area has lost feeling. Someone else may notice the color change first.

First Aid for Frostbite

Check for hypothermia first. If a person shows signs of both, the CDC says hypothermia is more serious and needs to be treated first.

For frostbite, the CDC recommends:

1. Get into a warm room as soon as possible.
2. Do not walk on frostbitten feet or toes unless absolutely necessary, as this increases damage.
3. Immerse the affected area in warm, not hot, water. The temperature should be comfortable to the touch for unaffected parts of the body.
4. Or warm the area with body heat. For example, frostbitten fingers can be warmed in an armpit.
5. Get medical care, especially if the skin stays numb, blisters or turns dark.

What not to do

• Do not rub or massage the frostbitten area. That can cause more damage.
• Do not use a heating pad, heat lamp, stove, fireplace or radiator to warm the area. The CDC warns that numb skin can easily be burned.
• Do not thaw an area if it might refreeze before you reach shelter. Refreezing makes the injury worse.

Build a Small Cold-Weather Kit

A few items, kept where you will actually have them, cover most city cold emergencies. Ready.gov and the American Red Cross recommend preparing winter supplies before the season starts rather than during the first storm.

For your commute bag or desk drawer:

• Spare dry socks, a hat and mittens or gloves
• A compact emergency blanket
• Hand warmers (the air-activated kind)
• A charged phone battery pack, since cold drains phone batteries faster
• A water bottle and a high-calorie snack; your body burns energy to stay warm

For home, in case the heat or power fails:

• Extra blankets and sleeping bags
• Warm layers for every household member, including hats for sleeping
• Flashlights and batteries instead of candles
• A battery-powered or hand-crank radio for updates
• Working smoke and carbon monoxide alarms with fresh batteries

If you drive, keep blankets, a shovel, an ice scraper, and extra warm clothing in the car. Our guide to ice storm preparedness covers the extra hazards of freezing rain, including falls on icy sidewalks.

Check on Neighbors and Watch for Warning Signs

Hypothermia often goes unnoticed because the person affected becomes confused and may insist they are fine. That makes other people the first line of defense.

During a cold snap or heating failure:

• Check on older neighbors and people who live alone at least once a day, in person if possible.
• Look for the signs listed above, especially confusion, slurred speech and drowsiness in a cold room.
• Ask whether their heat works and whether they have enough food and medication.
• Help them get to a warming center or a warm relative’s home if their apartment stays cold.
• Call 911 if someone seems confused, very drowsy or has a low body temperature.

Pets need protection too. Bring them inside during extreme cold; short-haired dogs and small animals are especially vulnerable.

Understand Wind Chill and Cold Alerts

Temperature alone does not tell you how quickly cold can injure you. Wind carries heat away from exposed skin faster, which is why the National Weather Service publishes a wind chill temperature.

The NWS Wind Chill Chart shades combinations of air temperature and wind speed where frostbite can occur within 30 minutes, 10 minutes and 5 minutes on exposed skin. At the more extreme combinations, the window for safe exposure becomes very short.

In October 2024, the NWS simplified its cold weather alerts. The products to watch for now include:

• Cold Weather Advisory: cold or wind chill conditions that could be dangerous without precautions.
• Extreme Cold Watch: dangerous cold is possible in the coming days.
• Extreme Cold Warning: dangerously cold air temperatures or wind chills are expected or occurring.

Sign up for alerts so these reach you automatically. Our guide to emergency alerts, weather radios and local sign-ups explains the options.

Dress for the Conditions

Prevention starts with clothing. Ready.gov and the CDC suggest:

• Wear several loose layers rather than one heavy coat. Layers trap warm air and can be adjusted.
• Choose a water-resistant outer layer to block wind and moisture.
• Cover the head, ears, face and neck with a hat, scarf or face covering.
• Wear mittens, which keep fingers warmer than gloves.
• Use insulated, waterproof boots and dry socks.
• Change out of wet clothing as soon as possible.

Carry spare socks and gloves in a work bag during cold months. A long walk home after a transit shutdown can turn into real exposure. Our guide to getting home when transit shuts down covers planning for that scenario.

Staying Warm Indoors When the Heat Fails

Cold injuries also happen indoors, especially during power outages and heating failures in older buildings. The NIA recommends that older adults keep their homes at 68°F or warmer.

If your heat goes out:

• Report it to building management or your utility immediately, in writing if possible.
• Close off unused rooms and gather in one room, preferably with fewer windows.
• Stuff towels or blankets under doors and cover windows at night.
• Wear layers, a hat and warm socks indoors, and use extra blankets at night.
• Never use an oven, stove or grill for heat. These can cause carbon monoxide poisoning or fires.
• Use space heaters carefully, keeping them at least three feet from anything that can burn, plugged directly into a wall outlet and never left on unattended.
• Find a warming center if your home stays cold. Many cities open them during extreme cold; check your city’s emergency management site or call 311 where available.

Our guide to winter storm preparedness for your home and car covers supplies for longer outages.

Frequently Asked Questions

What temperature is considered hypothermia?

The CDC defines hypothermia as a body temperature below 95°F. That is a medical emergency.

Can you get hypothermia when it is not freezing?

Yes. The CDC notes that hypothermia can occur above 40°F if a person is chilled by rain, sweat or cold water.

What are the first signs of frostbite?

Redness or pain in the skin, followed by white or grayish-yellow skin that feels firm, waxy or numb.

Should you rub frostbite to warm it?

No. Rubbing or massaging can cause more damage. Use warm, not hot, water or body heat, and get medical care.

Which is more serious, hypothermia or frostbite?

Hypothermia. If a person has signs of both, treat hypothermia first and call for medical help.

The Bottom Line

Cold injuries develop quietly, and the people affected often cannot tell. Learn the warning signs of hypothermia and frostbite, warm the core first, never rub frostbitten skin and get medical help when the signs are there. Watch NWS cold alerts, dress in layers with mittens and a hat, keep spare dry clothes in your commute bag and check on vulnerable neighbors when the heat goes out.