When temperatures start falling in the Upper Midwest, a line is drawn in the freshly fallen snow. For some, it’s time to hibernate for the season – bundling under blankets and streaming video for hours. But for others, it’s prime time for playtime outdoors.
Whether you’re cutting up the ice at your local rink, watching bobbers in your ice shack or shredding powder on the slopes, cold temps are the common denominator. And while numb fingers, chilly toes and frostbite are usually top of mind, there’s another danger that’s just as possible and even more serious – hypothermia.
Hypothermia can sneak up on your body without much warning, especially if you’re outdoors often in the winter. As you grit through the cold, what’s normal for your body? What’s worth taking a break to get warm or, even worse, what demands an ER visit? We’ll give you the details about what hypothermia is, how it happens, the damage it can cause, what to look for and when to get help.
What is hypothermia exactly?
Hypothermia is a medical condition where your body drops below its normal temperature, losing heat faster than it can make it. The longer it continues, the colder your body gets – putting you at life-threatening risk.
Normally, your body has an excellent internal thermostat. It knows when to burn calories when you’re cold and when to sweat when you’re hot. When all is well, your body keeps temperature between 97.5°F to 99.6°F (36.4°C to 37.6°C). For many, the ideal middle is 98.6°F (37°C). This range of temperature is where your body is at its most comfortable, with your organs able to run efficiently and without stress. Go above or below that temperature range and your body reacts appropriately to bring you back to the middle.
When you’re cold, your body reacts by converting more calories into energy, creating more body heat. However, that new heat can leave the body quickly, so your skin’s sense of cold sends signals to your brain to put on more clothes and find warm shelter. Your body needs that insulation and warmth to help equal out your internal temperature. Without that help, your body temperature can start to drop below its normal range.
Prolonged cold is not good for internal organs like your brain, heart and kidneys. A colder body temperature puts everything in survival mode, slowing the functions of your organs and redirecting blood flow to keep you alive. Without intervention, things can snowball fast, resulting in organ damage and even death.
Symptoms of hypothermia by stage
There are three stages of hypothermia, each with its own set of symptoms that become more intense the colder your body temperature gets:
1. Mild hypothermia
At the very beginning stage, your body dips just below your ideal temperature range. Starting at 95°F down to 89.6°F (35°C to 32°C), your body starts showing the initial signs:
- Cold skin that’s pale or off-color
- Numbness in your hands, fingers, feet and toes
- Behavior that feels “off” or abnormal – unsteady movements, slurred speech, poor judgment and lack of interest, concern or awareness
- An increased heart rate and faster breathing
2. Moderate hypothermia
As your body starts to get colder – between 89.6°F and 82.4°F (32°C to 28°C) – your systems are on alert, trying to redirect blood and warmth to keep you alive:
- Fading in and out of consciousness
- Urinating more as your kidneys become stressed
- Shivering stops completely, leaving your body still
- Your heart rate and breathing slow as your blood pressure drops.
3. Severe hypothermia
At 82.4°F (28°C), your body’s temperature is too cold to continue functioning and starts to shut down:
- Full loss of consciousness and responsiveness
- Body that is fully cold to the touch with stiff muscles
- Slow, irregular and faint heartbeat and breathing
It’s easy to think that something like hypothermia only happens in extreme, arctic cold. Unfortunately, exposure to cold is just one of many factors that can cause a drop in body temperature:
Let’s start with the basic cause of hypothermia – the temperature around you. Your body starts to be affected when the surrounding temperature is 50°F (10°C). Not freezing, but enough of a difference against your normal body temperature for your internal heating systems to get to work.
Notice how miserable you feel when you’re outside in wet, windy weather? That’s because wind and moisture have an amplifying effect on cold air – making it much more effective in chilling your body to the bone. Even if it’s warmer than 50°F (10°C) outside, it’s still possible to get hypothermia if the weather is rainy, windy or a combination of the two.
If your clothes or skin get wet, that can push your body temperature down further and faster. Moisture on the skin, like sweat, is your body’s natural way of cooling itself. And while that’s great when you’re warm, it’s dangerous when you’re already chilled. Plus, wet skin freezes more quickly than dry skin, putting you at extra risk for frostbite.
So it’s chilly outside, but it’s not freezing. It’s a dry, calm day with no rain or wind. But if you plan on being outside for a while, hypothermia is still something to watch. Over a long period of time, enough heat can leave your body to dangerously drop your temperature. Campers who sleep under the stars in spring and autumn know this well, making sure to keep bundled up if staying outside for days at a time.
Keeping heat from escaping your body is just as important, if not more than, the ability to make new heat. That’s why it’s crucial to have the right clothing for the temperature, weather and time you’ll be outside. Without the right clothing, your body will lose the heating battle, putting you in danger.
Who’s at risk for hypothermia
Anyone who is exposed to the right mix of temperature, weather, moisture and time without the right clothing can be at risk. However, there are those that are especially vulnerable:
Very young children
The little bodies of babies and infants don’t have well developed internal temperature controls or enough insulating body fat, making hypothermia a very real danger.
The older you are, the less your body is able to consistently control its temperature and produce heat. That, along with other health conditions, can make cold temperatures from both inside and outside especially dangerous.
Those under the influence of alcohol or drugs
The effects that drugs and alcohol have on your body in the cold can make it harder for your heart and brain to regulate your body temperature. Add to that the effects these substances have on your judgment and perception, and you may have a recipe for disaster.
People with low body fat
Body fat makes an extremely effective heat insulator in the winter. That said, those with low amounts of body fat – either from being extremely fit or very malnourished – are at a higher risk of hypothermia.
Hypothermia risks in Minnesota
Minnesotans are already experts when it comes to having fun in cold weather. But that doesn’t mean we are immune to the effects of hypothermia. Between 2002-2019, cold-related illnesses accounted for 588 deaths in the state of Minnesota, according to the Minnesota Center for Health Statistics. That includes a record 62 deaths in 2019 alone. Also, according to the Minnesota Department of Health, those over the age of 65 had the highest rate of cold-related deaths by a wide margin.
Of course, with our love of hockey, skiing, snowshoeing, ice fishing, snowmobiling and skating during the coldest days of the year, that means Minnesotans should be especially careful playing outside in winter. Caution is even more important when we’re working in cold weather, like when we’re shoveling out after a snowstorm. But there are other situations where our home in the Upper Midwest is especially prone to cases of hypothermia.
Lack of proper heating indoors during the winter is especially dangerous – particularly for older adults at risk. Without enough heat and insulation, hypothermia can set in gradually throughout the day and night. Fortunately, Minnesota has a cold weather rule in place that protects against having your electric or natural gas being turned off between October 1 and April 30. There are also programs offered by utility providers like Xcel Energy and CenterPoint Energy to help with energy bills throughout the year.
Autumn and spring activities
While the winter’s bookend seasons of fall and spring are relatively warmer, temperatures can still drop below that important 50°F (10°C) mark. Those that stay outside for hours on end, like campers and hunters, are especially at risk.
On the water
On a boat, on skis, off a dock and in suits, Minnesotans are constantly near and in water. But even when it’s warm out, water is still a prime place to catch hypothermia fast. If you find yourself in or around water that’s below 70°F (21.1°C), be extra careful. Water can conduct heat away from the body 25 times faster than air. Fall in or stay in too long, and you can be at risk for immersion hypothermia – a very dangerous situation that can come on quickly.
Treating hypothermia and when to get help
The key to treating hypothermia is to catch it early. If you feel the initial symptoms of hypothermia, or see it in a person you’re with, act quickly. You may think you’re overreacting, but remember that one of the first symptoms can be poor judgment. Playing it safe and getting warm is never a bad thing.
At the first symptoms of mild hypothermia (shivering with cold, numb skin and unusual behavior):
- Stay calm and avoid anything that can cause you to sweat (which can cool you down faster)
- Get to warm shelter, or at least out of direct cold, wind or moisture
- Remove any clothing that is wet or moist
- Surround yourself with dry clothing and blankets
- Sit close to a source of dry heat, like a propane heater or fire
- Drink warm beverages, like hot chocolate or broth (avoid anything that has alcohol or is high in caffeine)
- If available, use a hot water bottle to warm areas of your body that are especially cold
However, if symptoms don’t get better or if they get worse – especially if you see things like slipping in and out of consciousness or lack of shivering – call 911 and get emergency help immediately. In transit and at the hospital, EMTs and care teams have many ways to treat hypothermic patients, including the use of warm intravenous saline solution, humidified oxygen, and drawing, warming and recirculating the blood using a hemodialysis machine.
It’s easy to both have fun and stay safe – all you need is the right clothes, good awareness and a plan for where to get warmth and help if you need it.
You probably know the basics: dress in layers, complete with warm jacket, hat, socks and boots. Gloves are fine, but mittens are even better when it comes to keeping your hands warm. A face mask is also a good idea for longer, windier trips. It’s best to dress in wool or synthetic fabrics – they’re excellent at insulating heat and won’t absorb moisture and cling to your skin like cotton. And if you’re going to be on the water, make sure you wear a life jacket, so you’ll float and be easier to spot if you fall in unexpectedly.
Know your limits
The person that knows your body best is you. Know ahead of time what your limits are when it comes to cold and when you need to go inside to get warm. Don’t be so brave that you put yourself in danger, especially if you’re on your own. Consider setting a timer on your watch or smartphone to get back into shelter after a set amount of time.
Make help easy to get
As you’re having fun, make sure you know where you can get warm when you need to. It’s even better if your shelter from the cold has direct access to a landline phone in case you need emergency help. If you’re venturing farther out, make sure you have a phone that is in service, charged up and ready to go if necessary.
Stay safe and have fun this winter
Before you head out for good times in the cold, check out our other posts, including the link between cold weather and heart disease, how to properly prepare for running in the cold, and why Raynaud’s disease may be the reason your fingers turn white or blue in the cold.