Temperature Extremes and Related Conditions



Hiking in the hot, dry environment of the desert creates some special considerations. When doing especially difficult hikes which involve climbing, the exertion required accelerates the effects of fatigue. When hiking during the summer when temperatures are high, dehydration can lead to heat exhaustion.

Here are some tips for hiking in extreme heat.  Then, read on for a better understanding of heat-related conditions to be watchful of on the trail.

Dehydration occurs when your body loses too much fluid. This can happen when you stop drinking water or lose large amounts of fluid through diarrhea, vomiting, sweating, or exercise (such as hiking). Not drinking enough fluids can cause muscle cramps. You may feel faint. Usually your body can reabsorb fluid from your blood and other body tissues. But by the time you become severely dehydrated, you no longer have enough fluid in your body to get enough blood to your organs. In the early stages, you may be able to correct mild to moderate dehydration without the intervention of medical professionals, by controlling fluid losses and replacing lost fluids.

If you become mildly to moderately dehydrated while working outside or exercising:

  • Stop your activity and rest.
  • Get out of direct sunlight and lie down in a cool spot, such as in the shade or an air-conditioned area.
  • Prop up your feet.
  • Take off any extra clothes.
  • Use a wet cloth to moisten the skin & provide an evaporative cooling effect.
  • Drink a rehydration drink, water, juice, or sports drink to replace fluids and minerals.


Early symptoms of heat exhaustion are minimal or no urination, loss of appetite, and loss of thirst. These symptoms can quickly progress to extreme fatigue, headache, fainting, nausea, and vomiting. While this condition is best prevented by resting, eating, and drinking during one’s hike, a hiker can slowly recover by following this same advice once symptoms develop. Full recovery, however, can take days. It is not advisable to hike during mid day heat. Always carry a flashlight so that hiking after dark is a reasonable alternative if it becomes necessary.

More serious illnesses associated with desert hiking are water intoxication and heat stroke. Water intoxication (hyponatremia) is an illness that mimics the early symptoms of heat exhaustion, except that urination is frequent, a higher volume than normal, and clear. If left untreated, advanced symptoms include behavioral changes, diarrhea, and unconsciousness; these symptoms often require hospitalization. Water intoxication can occur when a person drinks excessive amounts of water and eats very little or not at all, creating an electrolyte imbalance. To prevent and treat early stages of water intoxication, eat! Consider using one of the many electrolyte drink mixes, such as Gatorade to supplement your water supply.

Heat stroke is a life threatening emergency which can occur when a person hikes through the mid day heat without taking the time to rest and cool their body. Early symptoms include unusual or illogical behavior, elevated temperature, flushed appearance, and weak, rapid pulse. The condition can rapidly progress to unconsciousness, seizures, and death.

The heat stroke victim must be cooled immediately! Continuously pour water on victim’s head and torso, fan to create an evaporative cooling effect, move victim to shade, and remove excessive clothing. The victim needs evacuation to a hospital. Someone should go for help while attempts to cool the victim continue. It is far better to prevent this situation: avoid the mid day sun and cool off in shade or near water sources when available. Use your water supply to wet your hat and shirt during your hike. Avoid direct exposure of your head and torso to the sun.

Hypothermia can also develop in a desert hiking environment, particularly if a hiker is fatigued. While hypothermia is most often a concern during the winter season, it can occur at almost any time of year at higher elevations. Night time temperatures at higher elevations can drop significantly, even in summer. Hypothermia can occur at temperatures in the 50º range, especially when a tired hiker is also experiencing wet, windy conditions. Symptoms include uncontrollable shivering, poor muscle control, and careless or illogical behavior.

To prevent hypothermia, wear wind and water resistant outer clothing and synthetics capable of wicking moisture away from your skin. It is important to eat high energy foods and drink warm fluids to increase your body’s resistance to the effects of cool temperatures.
Your body spends an enormous amount of energy (good calories) keeping you cool while hiking in the heat. Eating is your most important defense against exhaustion and water intoxication. Food plays an important role in keeping your body cool:

  • Eat twice as much as you normally do.
  • Eat before, during and after you hike.
  • Eat before you are hungry.
  • Eating small amounts of complex carbohydrates (breads, fruits, crackers, grains, energy bars, etc) throughout the day (every 15 – 30 minutes on a long hike) will help keep you energized.
  • The body’s cooling system needs adequate water. Drink appropriate amounts of water; electrolyte supplements are helpful. At the same time do not over drink. Monitor you urine output.

Hiking in higher temperatures causes one to sweat around .5 to 1 quart of water and electrolytes every hour while walking in the heat. This fluid/electrolyte loss can even exceed 2 quarts per hour if you hike uphill in the direct sunlight, and during the hottest time of the day. Because desert air is so dry and hot, sweat evaporates instantly making its loss almost imperceptible. This evaporation allows our bodies to lose heat and keep cool. Do not wait until you start feeling thirsty to start replacing these fluids and electrolytes. By the time you feel thirsty, you are already dehydrated. Even this mild level of dehydration can make you approximately 10% to 20% less efficient, and this makes hiking a lot less fun. The more dehydrated you become, the less efficient your body becomes at walking and cooling.
Your body can only absorb about 1 quart of fluid per hour, so drink .5 to 1 quart of some type of electrolyte replacement drink each and every hour that you are hiking in the heat. Carry your water bottle in your hand and drink small amounts often. The average adult should drink approximately 4 quarts of electrolyte replacement drink for every 8 hours spent hiking in the heat.

Hike wet! Soak down your cotton clothing (hat and tee shirts) at every water source opportunity. This is one of the best things that you can do for yourself. Whenever you are near water, make sure that you wet (actually soak) yourself down. If you hike while soaking wet – you will stay reasonably cool. This will make a wonderful difference in how well you feel, especially at the end of the day!

Staying Dry in the Rain

For further optional reading, here are some tips on staying warm & dry while hiking in the rain.


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