How to Prevent Hypothermia While Hiking and Backpacking

By Michael Lanza

Rain and wind battered two friends and I as we hiked across exposed meadows high in the Olympic Mountains—our second straight day of heavy rain. Dripping, knee-high vegetation ladled cups of water onto our pants and boots. My rain jacket kept my upper body dry, but my soft-shell pants eventually soaked through. That, and the wind, slowly made me steadily colder—more than I realized.

After a strenuous ascent of a steep mountainside, carrying a heavy pack with my jacket hood up—which should have made me quite warm—it occurred to me: I’m still cold.

I was hypothermic.

What’s more, we had all—ironically, given the rain—run out of water more than an hour earlier. We undoubtedly hadn’t eaten enough to replace the calories burned through a full day of hard hiking in cold wind and rain. Now, as the rain continued pounding us, night approached and we were nowhere near a water source or flat ground for camping.

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Backpackers hiking in rain in the Bailey Range, Olympic National Park.
Jeff Wilhelm (behind) and me hiking in rain in the Bailey Range, Olympic National Park.

We understood that our situation was serious. We calmly discussed our priorities. First and foremost, we needed a spot to pitch our tents—under the circumstances, shelter was more important than water, because we knew we could survive a night without water and that we’d find some in the morning, and we had plenty of food. But a night without shelter in those conditions posed far greater risks.

We backtracked to a flat area we had recalled passing about an hour earlier. The rain stopped before we set up camp, and we spent the night dry and warm in our tents. Clear skies greeted us the next morning. Two hours after leaving that camp, we reached a creek and drank copiously. We had gone about 20 hours without water, but hadn’t felt any serious effects from dehydration. Prioritizing shelter and warmth had been the right call. And I was amazed at how juicy dried mangoes taste when you have a raging thirst.

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Hikers on Besseggen Ridge in Norway's Jotunheimen National Park.
Jasmine and Jeff Wilhelm hiking Besseggen Ridge in Norway’s Jotunheimen National Park.

If you’ve spent much time outside in wet, cool, or cold weather—as I have over four decades (and counting) and thousands of miles of backpacking, including the 10 years I spent as Northwest Editor of Backpacker magazine and even longer running this blog—you’ve probably been at least mildly hypothermic. Most likely, it wasn’t serious and you easily remedied the situation with clothing, food, or shelter, by descending out of the wind, or some combination of those typical strategies.

But hypothermia isn’t like an ankle sprain, occurring suddenly and broadcasting its symptoms clearly. And it isn’t like hunger, always remedied with a quick fix.

It can happen quickly, or it can sneak up on you slowly. It may happen even when you believe you’re dressed well, because you didn’t initially feel cold. While it’s an obvious threat in the dead of frigid winter, it happens perhaps more often on cool, windy days in spring and fall, and certainly can happen in the mountains in summer.

Hypothermia can present a minor obstacle if recognized and addressed soon, or escalate into an emergency and even prove fatal.

Plus, as those two friends and I discovered that day in the Olympics, hypothermia can happen to anyone—even very experienced backpackers (and two of us were experienced climbers) who’ve endured severe weather numerous times.

In this article, I’ll explain what hypothermia is and how it happens, and offer expert tips and skills on how to avoid hypothermia and treat it when it happens to you or a companion, drawn from my decades of wandering through the backcountry in all kinds of weather, all over the U.S. and the world (and shivering more times than I could estimate).

Trust me when I say this: Someday, you will use these tips.

Please share your own tips, questions, or thoughts in the comments section at the bottom of this story. I try to respond to all comments. Click on any photo to read about that trip.

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A backpacker at 12,240-foot Knapsack Col, Wind River Range, Wyoming.
Mark Fenton at 12,240-foot Knapsack Col, Wind River Range, Wyoming.

What’s Hypothermia?

Hypothermia is defined as a core body temperature of 95° F/35° C or lower, which is about three degrees Fahrenheit below the average normal body temp of 98.2° F/36.8° C (although “normal” can vary from 97° to 99° F between individuals). Hypothermia occurs when someone is losing body heat faster than they can produce it, causing the body’s core temperature to drop.

While it’s hard to find statistics on how many hikers die from hypothermia, according to the Centers for Disease Control, an average of 1,300 Americans die from hypothermia every year. While most of those victims are undoubtedly nowhere near the backcountry, according to the National Park Service (reported in this Washington Post story), “cold exposure” accounted for about 25 deaths in all national parks between 2003 and 2007. That’s actually far fewer than deaths from falls (about 175), vehicle accidents (over 250), and drownings (over 350).

Still, hypothermia poses a significant risk to backpackers, dayhikers, climbers, and others in the backcountry. Preventing it begins with knowing how to recognize it.

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2 thoughts on “How to Prevent Hypothermia While Hiking and Backpacking”

  1. Michael, Great article for a serious problem in the backcountry. I’ve experienced hypothermia twice while hiking and witnessed several people with it on the summit of Whitney on a really bad weather day several years ago. It is something that few people prepare for and few know what to do once they start to exhibit the symptoms. While hiking, hypothermia and altitude sickness are always in the backs of our minds as there is nothing that slows down or cancels a trip quicker. ATB, Wayne