Preventing Hypothermia in the Backcountry

In October of 2018, I embarked on a solo journey to Mount Olympus in Washington state via the Hoh River Trail. There are inherent risks to hiking solo, but it’s my opinion that if you’re prepared, get out and explore. 

For this adventure, I was somewhat prepared. October is shoulder season and the weather in the Pacific Northwest is highly unpredictable, especially this time of year. The days were warm and pleasant, and I could hike comfortably in light pants and a t-shirt. Synthetics and wools were my layers of choice, driven by my concerns of sweating. I planned to wear synthetics during the day, which help draw moisture away from the body, as well as packing a change of clothing for the nights to keep myself warm and dry.

The morning that I was going to make my way to the summit started well before sunrise. It was cold and drizzling, so I was tempted to throw my warm clothes on from the onset, but I knew you should always “start cold” because your body will warm up from exertion along the way. 

Expect the Unexpected

I started with a merino wool base layer, a synthetic t-shirt, and a waterproof outer layer. I packed a light mid-layer jacket, as well as a wool puffy insulating layer, gloves, and a wool cap, which proved to be useful later. To make a long story short, I experienced a series of climate changes on my five-mile trek to the summit, from 60’s and sunny to a complete whiteout from a pop-up snowstorm about a half mile from the summit. This caused me to turn back, and on my way down I lost my footing on some slippery rocks and tumbled about 100 feet down an avalanche chute, landing on an outcropping about the size of a tabletop.

A view of Seth’s accident site from the SAR helicopter

I was busted up badly, and I couldn’t move or do anything to improve my situation. The weather kept changing from rain to sleet to snow and back, and I had no shelter with me (a learning moment for me to ensure I always need to carry The 10 Essentials). Fortunately, I did have an SOS device with texting capability, which no doubt saved my life. 

I was able to reach out for help, but due to the distance to the nearest ranger station and the severe weather which has already moved in, it was going to be a while before anyone could get to me. Luckily, I had those extra layers and was able to put those on and hunker down until help finally arrived via a Navy SAR helicopter some 18 hours later.

My Clothing Saved My Life

There is no doubt in my mind that the clothing I was wearing saved my life by protecting me from the elements and aided in maintaining some body heat during what was a very long, cold night. On a side note, when I was rescued, my expensive technical clothing was cut off by the paramedics in the helicopter to assess my injuries. I sent pics of my cut off clothes (and my story) to both Outdoor Research and Prana, whose gear I happened to be wearing. Both companies replaced everything that had their names on it free of charge. Both are stand-up companies, and I will forever be an ambassador for their gear.

This experience started a cascading effect that has ultimately led me to become the person I am today – a Wilderness First Aid (WFA) instructor and outdoor enthusiast. As a result, I think I know a thing or two about how to properly layer your clothing in the backcountry during cold/inclement weather to stay safe and prevent hypothermia. 

Definition of “Cold”

Heat is a measurable form of energy that is typically expressed in temperature (or BTUs). When we say we “feel cold,” what we’re really saying is “my body is losing heat faster than it can replace it.” How does that happen? Good question.

Our bodies are always producing heat (it’s a function of being alive), even when we’re resting. Heat production varies depending on several factors including activity level, caloric intake, body mass, and genetics. The key to retaining heat is to understand the ways in which heat loss occurs, which is what we’ll discuss next. 

Heat

Heat is lost (or gained) through one (or a combination) of four specific processes: 

• Conduction

• Convection

• Radiation

• Evaporation

Conduction

Conduction is the transfer of heat through direct contact. Think about sitting on the cold ground for a moment. If your body is warmer than the ground, that heat energy from your body transfers to the ground instead of staying put and keeping you warm. We can combat this simply by putting an insulating pad or layer in between us and whatever is drawing the heat away from us. Conversely, this can also work in our favor to keep us warm. For example, sleeping with bottles of warm water between your legs in your sleeping bag, or sitting on a rock that has been warming in the sun all day. 

Convection

Convection is the transfer of heat through direct contact with air or water. In fact, direct contact with air or water can remove heat at a rate 25x that without! Protecting yourself from the elements like wind, rain, and snow is going to be key to keeping that precious heat where you want it-inside you. 

This can be accomplished by something as simple as seeking shelter. If you can keep the wind and water from hitting your body, it won’t be able to carry the heat away. “Shelter” doesn’t necessarily mean getting behind a large object or inside a structure. You can shelter yourself using careful preparation in the clothing you choose for your adventure. This is important to keep in mind every time you venture into the outdoors and is often underestimated or overlooked. Choose your clothing wisely. 

Radiation

Radiation is the “transmission of energy waves through space”, like warming yourself by a fire or in the rays of the sun. Radiant heat won’t penetrate through wet clothes, so it’s important to make sure those are removed before using the sun or a fire to warm your body. 

Radiation is also the primary mechanism by which Mylar or “space blankets” work. They trap heat from an energy source and radiate it back to your body. As mentioned earlier, your body is always producing heat, and a Mylar blanket can be very efficient at trapping the body’s heat energy and radiating it back to you. 

Mylar blankets are most effective when placed directly against the body (under clothing if possible) but are still effective while used on top of clothing as well. As a point of reference, however, if you’re trying to warm yourself from the sun or a campfire while wrapped in a Mylar blanket, know that much of the heat won’t make it to you as the blanket will be reflecting it away. 

Evaporation

Sweating is your body’s mechanism for releasing excess heat. When your brain senses a buildup of excess heat it transfers some of that heat to the surface of the skin. 

At the surface of the skin, that heat is further removed by the process of evaporation. Evaporation is when a liquid turns into a gas by being absorbed into the surrounding atmosphere. This is often hindered by the humidity that is already in the air. Hence when the humidity is high outside, the air molecules are already full of water, and the sweat from your body has no place to go. It sits on your skin or in your clothing and can’t evaporate. 

Imagine what happens as the temperatures cool at night. Remember, convection removes heat 25x faster. As a result, you can see how this can quickly lead to hypothermia.  

Seth layering system at the start of his trek.

Layering

Layering is the act of adding (or removing) layers of clothing to keep you warm or cool you down. The latter is a critical component to prevent sweating, and potentially, hypothermia. 

Based on the weather and the elements you’ll be exposing yourself to on your next adventure, be sure to carrying the following layers:

• Base Layer

• Mid-layer

• Insulating Layer

• Wind/Rain Layer (Outer Shell)

Base Layer

This is the layer that is in direct contact with your skin, so it’s crucial that it is a material that wicks sweat instead of trapping it next to your body. I prefer Merino wool. It’s lightweight, comfortable, wicks moisture and dries easily. Also, wool is naturally antimicrobial, so it tends to stink less after wearing it for several days. There are several other good options with synthetic materials such as Capilene, silk, and polyester, or a combination of them. Insulating values can vary based on your activity and climate, but remember a little can go a long way. Lightweight or midweight is typically sufficient unless you’re going to be inactive for long periods in arctic conditions. 

Mid-layer

Again, there are loads of options here which include many different synthetic materials such as polyester fleece and some naturals like wool and alpaca. For my trip to Olympus, I chose a lightweight zip up hoody made by Mountain Hardwear. This was my top layer for most of my hike unless it was raining, because it protected me from the sun at higher elevation but wasn’t overly hot while I was active. The zipper gave me the ability to open it up even more to “air myself out” or even remove and put it back on at times. 

Avoid cotton at all costs. No matter how awesome that concert tee or sweatshirt would look in the summit pic, cotton will trap the moisture that the base layer wicks from your body and when the ambient temp drops, so will your body temp. 

Insulating Layer

My go-to insulating layer is a good old down puffy. Down is hard to beat for its insulating properties and light weight. Most of them will pack into their own pocket, so space shouldn’t be a concern. There are some synthetic alternatives that come very close, but it’s really hard to beat down’s warmth to weight ratio. Realistically you will have this with you and probably only wear it when you’re stopping for an extended period of time. I didn’t get mine out until I was laying on the ledge, but boy was I glad I had it. 

The only negative with down is that it doesn’t insulate well when wet, so the outer shell is critically important. If something is going to have direct contact with the elements like a hat or gloves, down is less than ideal, with wool being your better option, especially for hats. 

For hand protection, mittens are typically warmer than gloves because they allow for more air to circulate around the fingers. There’s a trade-off in dexterity, though. For my trip I wore wool gloves, but packed a set of waterproof “shell” mittens to wear over them if my hands got cold (and they did). 

Wind/Rain Layer (Outer Shell)

Every outdoor retailer and clothing manufacturer has a plethora of waterproof and breathable outer layers, including jackets, pants, hats, gloves, boots, socks, etc. - you name it. It’s hard to make a recommendation here because the technology changes so fast and really just keeps getting better. You’ll have to do some research, and decide what is most important for your situation. 

In my experience, ALL shell layers trap heat in close to your body. Great if you’re standing still, not so much if you’re moving. I like pit-zips to give me an extra ventilation option. 

If a brand claims their rain jacket is waterproof, don’t believe it. At best, they’re water resistant, and even then, all rain jackets are prone to “wetting through” when exposed to rain or snow ofor long periods.  

I’ve had really good luck with Gore-tex treated fabrics, although it’s not as breathable as other fabrics. Just remember, typically the more protective it is, the less packable it is, so be prepared for the trade-off. 

The SAR team that saved Seth’s life.

Summary

Keeping yourself warm as you adventure into the backcountry this winter isn’t exactly rocket science, but it is science. The trick to retaining your precious heat is in understanding how it is lost and being able to correct it before or shortly after it happens. Remember some of these key points:

1. Plan ahead and choose the right gear. We are lucky to have so many options when it comes to this. Do your research.

2. Seek shelter from the elements whenever possible. This could mean a structure or the clothing you have with you. Note: There are waterproof bivy sacks that can fit in your pocket.

3. Stay dry. Sweat is the enemy! Start your hike cold and dress in layers that can be easily added or removed. This includes hands and feet.

4. Use what nature gives you when you’re in a pinch. Use leaves or pine needles to make a cushion to insulate yourself from the ground. Also, the sun can be a powerful source of warmth but use caution to protect your skin as well. Even when it’s cold, you can still get sunburn from too much direct exposure.

5. Calories= heat. Calorie dense meals require your body to work harder to break down and process the food, thus creating heat from within, so eat up!

My experience on Mt. Olympus was life changing in many ways, and it taught me a lot of things. One is that experiences like mine are not as uncommon as you think. People actually get caught off guard by the elements a lot and, if you’re in the backcountry, that’s a true life and death situation. Those that survive are either lucky or prepared - or even both, as it was in my case. Another thing I learned is that you can survive a long time with a little bit of knowledge, the right gear, and a will to live. 

I hope you never have a similar experience in your adventures, but maybe mine will help you if you ever do. Staying comfortable outdoors is the key to enjoying it. Hopefully this article gives you a better understanding of how to do that. Now go out and get exploring!