Hal Koerner’s Guide to Running in Bad Weather and Trail Conditions

This excerpt comes from Hal Koerner’s Field Guide to Ultrarunning, a comprehensive handbook to running 30 to 100 miles and beyond, written by Hal Koerner, one of the most experienced and recognized athletes in the ultrarunning.

Chapter 6: Dealing with Your Environment

Few ultras are held in urban environments; the vast majority of routes run through natural settings where the scenery helps inspire you across the distance. Although many runners have a deep affection for wilderness, they are not necessarily versed in what it’s like to be deep within it for many hours. Being prepared for wildlife encounters, knowing how to purify water, and getting comfortable on challenging terrain such as ice, snow, mud, and technical footing are crucial tools in your ultra toolbox. Similarly, it is invaluable to be able to handle running in cold conditions, to know how to deal with hot temperatures and how best to cope with running at higher elevations or at night, and, most important, to know how to stay found out there (that is, unless you are mastering the finer details of going to the bathroom in the woods).

Running in Mud

Running in mud can present a few unpleasant challenges. Thick mud can pack into the bottoms of your shoes, adding what feels like a ton of extra weight. A gunked-up bottom means significant loss of traction, as well. Finally, as you tire, dredging through mud can lead to muscle strains, cramps, and pulls as the tackiness of the mud causes you to stride differently and exert your fatigued and electrolyte-depleted muscles.

Your pace and stride are going to slow and change in mud. Be prepared to be on all fours on a muddy incline, if necessary, using your hands to get traction. Try to stomp off as much mud as possible or wipe off what you can on a rock. Many trail running shoes have self-cleaning soles, making them more effective at shedding mud than road shoes. Some trail shoes, however, actually hold on to mud, depending on the outsole pattern, the depth of the lugs, and the particular mud type. Certain clay will stick to any shoe, regardless of the sole surface. When you buy your shoes, it pays to inquire specifically about their various features to ensure you are getting what you want.

Getting dirty is a part of trail racing. Embrace it if you can. The North Face championships in 2012 turned out to be a mud bowl of epic proportions. Some runners were completely defeated by it. Watching them slog through the course, you could see they had no motivation, no momentum. For them, the course was miserable and went on forever. Others, however, ran through it like kids playing in mud puddles, embracing it and having a good time with it. Same conditions, different attitude—and most likely different end result, too. Yes, mud can be frustrating, but staying positive will get you through the course in better fashion and likely at a faster pace. Remember, it’s just another variable to hurdle! Roads are predictable. That’s why we love trails, right?

Running on Ice

The best solutions for confronting icy conditions are hobnails, which are screws you put into your outsoles, carbide-spiked trail shoes, and MICROspikes, removable minimal crampons that bite into the ice. I favor MICROspikes because they can be quickly slid on over your shoe when conditions get dicey and then easily removed when you are on firmer ground, and they are also light, efficient, and pretty easy to carry. There are other types of traction devices, such as traction cleats that are based on a spring system rather than teeth, that are good for walking and hiking. They are not as effective in running, however, because the spring can snap under the greater weight and impact.

Good technique on ice includes being very focused; taking shorter, faster, lighter strides with a wider stance for better balance; having your hands as free as possible; and slowing your pace appropriately for the conditions.

Running in Snow

The first thing to remember about snow is that it has many different personalities. It can be soft and powdery, heavy and wet, or hard packed, with each type creating its own potential hazard. Running in wintry weather means you can be enjoying an easy day, glissading down a peak, for example, and the next thing you know you are on rock-hard ice! This abrupt change presents a dangerous situation, so be familiar with what you are running on and remain alert to temperatures and terrain changes.

When you head out in snow, stay protected from the elements as best you can. Cold and its more menacing partner in crime, frostbite, can end a run quickly. Staying protected means having full coverage from your feet on up. It is common to break through the upper crust of older snow, only to ram your shins into the hard surface and cut yourself. Because of this, capris aren’t a wise choice when the course is likely to cross through snow fields; go with tights or pants instead. Also, wear higher socks, which can go over or under tights and provide much-needed insulation on your ankles, where abrasion, exposure, and frostbite are common. Further, toe socks are a potentially hazardous choice in the cold; better to allow for the heat that grouped toes create. Wear wool and technical materials, not cotton, which will chill you when it gets soggy.

As for shoes, regular shoes and wool or at least wicking socks are probably all you will need, especially in dry, light snow. In heavy, wet snow, Gore-Tex shoes can provide waterproof protection, but they can also trap water inside, adding weight and creating an unpleasant feeling, as well increasing your susceptibility to blisters. Regarding the outsole, some rubbers are better than others in snow. If you are running in a lot of snow, the main thing to look for is an aggressive tread; this helps with confidence and keeping you upright.

I like to dress in layers, such as a long-sleeved shirt coupled with a vest that covers my core but allows unrestricted arm movement. I really like wool tops, which are great insulators; wool is a natural fiber and a warm option that also works well to wick moisture as the temperature rises. These days, with advances in technical materials, you can get away with a stand-alone piece more than you used to, saving you from the need for multiple layers and having a bunch of extra clothes to deal with as you warm up.

A hat is a must: It covers your ears, an area sensitive to frostbite, and keeps you from losing heat through your head. Gloves or mittens for your hands are also essential. Gloves are a practical choice because they allow you to tie your shoes, get into zippered pockets, adjust your audio, and so on. However, mittens pool the warmth of your whole hand and are a better choice if you are concerned about frostbite. Fortunately, there are convertible mitts, which provide the dexterity of a glove with the warmth of a mitten, as a great hybrid option.


  • Come prepared with everything you may need, using drop bags or layering on your person as is practical.
  • Dressing in layers is key. Today, technical materials and clothing are so thin and lightweight, there is no excuse for not carrying them along with you if you know you may be facing cold conditions. Calf or arm sleeves are a great option for added warmth and are easily removed.
  • Dehydration can lead to getting too cold, so stay on top of your hydration.
  • Make sure you are getting warm liquids to help warm your core. Many aid stations will have soup or oatmeal available.
  • Make sure you have hats, gloves, and extra socks (wool). Even if you don’t have to replace the socks you are wearing, the extra ones make handy mitts if you need them.
  • Do your due diligence: At what point in the race might you need items such as a hat or parka? Plan accordingly.
  • Never underestimate nighttime temperature swings, especially at altitude. Too, if you end up having to walk or stop, that’s when you get the coldest. The heat you were generating while running gets lost, and you can go into a hypothermic state, especially if your base layers are wet from sweat. So if you encounter large drops in temperature, make sure that you keep moving to generate heat, even accentuating movements more than you otherwise would.


 Hypothermia occurs when the body’s core temperature drops so low that the body loses its ability to manage its temperature. It usually occurs as a result of external circumstances, such as a drop in outside temperature combined with insufficient clothing or layers, and then can become compounded if you are not taking in enough fluids or nutrition to help combat it.

As temperatures drop, you require more calories to stay warm. So you must fuel beyond what you need simply to get through the miles; you also must fuel to meet the demands of your environment. To make it worse, if your pace falls off, or you pause at an aid station, you stop generating heat through running, just when you need it most.

While it takes time to reach a hypothermic state, the symptoms can come on quickly. They include uncontrollable shaking, numb extremities, a feeling of cold that goes all the way to your core, blue lips, and chattering teeth.

Know where you are going to be running and the potential extremes. If you know you will be on high peaks, at altitude, in exposed, windy areas and in certain types of weather, be prepared with clothing, either in your pack, left in an appropriate drop bag, or held by your crew. I have seen the weather change in an instant at races. At Leadville, which takes place in August, you may find yourself sifting through snow at the top of Hope Pass; for a runner who is unprepared, this could dampen even the heartiest ambitions.

One of my first 100-milers was the Iditasport in Alaska. This race is run along the famed Iditarod Trail as well as frozen lakes and streams. You must navigate snow machines and teams of mushing dogsleds, as well as snow and freezing temps in the mid-February darkness. I had been leading most of the race with another competitor when things took a turn for the worse. I went for a long stretch without water after my hydration pack became clogged with electrolyte drink powder. Although I had taken the necessary precautions to make sure I had insulated tubing, I hastily (and mistakenly) added the mix first instead of my water; this choked my water supply by pushing the mix into the tube.

Because I was afraid of getting lost, I opted to stay close to the runner ahead of me rather than take time to stop and fix my bladder. I’d like to say that was my only error, but, unfortunately, both that runner and I ended up getting lost later on just when I couldn’t afford more time out in the elements. To add insult to injury, we ran on unstable frozen water that had pooled above the ice, drenching our shoes and pants. Recipe for disaster? You bet. Without water, without sufficient calories to compensate for getting lost, and now hypothermic, I went from leading the race to barely finishing the next day, after spending some 5 hours in a warming hut.

The good news is that aid stations usually have warm liquids and often a heat source, such as a fire or heater. If you are not prepared, beware. You can be removed from the race for hypothermia, and rightly so, because it can become a serious health concern if not arrested.

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