Safe Hiking in Hot Weather

Take Precautions When You Hike in Hot Weather

Desert hikers aren't the only ones who have to deal with hot weather in summer. Take precautions to prevent dehydration and heat-related illnesses when you hike on hot days. © Matt Jaffe, 2011

Summer means preparing yourself for hiking in hot weather. Dealing with heat is a fact of life and not just on desert trails.

High humidity can send the heat index (how hot the combination of air temperature and relative humidity feels to your body) well above 100 degrees, even in northern parts of the country.

So no matter where you live, it’s critical that you pay attention to weather conditions before you head out for a day of summer hiking. Other than simply not hiking, there’s no way to completely eliminate the risks. But you can greatly reduce the dangers by taking basic precautions.

Planning Ahead

  • Pay attention to weather forecasts. Sites like let you check forecasts by location and ZIP code. The site offers hourly temperature predictions for the current day and every three hours for the following day.
  • Don’t be overly ambitious. A hot day isn’t the best time to finally do that 10-miler with 2,000 feet of climbing. If you’re intent on getting out, scale back your expectations and save the tough trails for another day.
  • Choose the right hike. If you live in an area with topographical variation, look for higher elevation trails. Hikes along the coasts or other large bodies of water, such as the Great Lakes, will also be cooler than inland trails.
  • Hike early in the day. Temperatures can easily be 20-25 degrees cooler in the morning than in the afternoon. The day will cool off toward sunset but temperatures will still be much hotter than in morning.
  • Avoid the most intense sun. Direct sun will increase heat-related stresses and the risk of sunburn. Try to find shaded trails and avoid hiking between 10 and 4.
  • Keep it loose and light. When it comes to clothing, remember “The Three L’s:” Lightweight, loose-fitting, light-colored.
  • Wear a hat. A lightweight, light-colored hat with a broad brim to keep the sun off your face and neck will help you stay cool. Nothing fancy either: You’ll want a hat that you’re willing to soak with water from a creek or lake. There are also many lightweight hiking hats on the market that help block UV rays.
  • Use (and pack) sunscreen. Exposed, sunburned skin will only make it more difficult for your body to stay cool.


On hot days, your body can lose large amounts of water through perspiration. The general rule is that you can sweat roughly a quart of water every hour—and even more when hiking uphill or in direct sunlight. Hiking at higher altitudes will also accelerate the loss of body fluids. In arid climates, you may not even notice how much you’re sweating because of rapid rates of evaporation. And as you perspire, you also lose vital minerals from your system.

Proper hydration is essential to the health of the body’s organs, including the brain. Dehydration can lead to impaired brain functioning, which then results in confusion and impaired judgment. Blood can also thicken, forcing the heart to work harder.

  • Start the hydration process before you go out. Begin to hydrate a couple of hours before you hit the trail.
  • Pay attention to your body. Don't ration water. If you are thirsty, drink. When you're halfway through your water supply, it's time to turn around. 
  • Drink frequently. Instead of guzzling a bunch of water all at once, take smaller and more frequent drinks of water.
  • No, beer doesn’t count. Alcohol can speed up dehyration because it’s a diuretic. So will caffeine-laden energy drinks.
  • Check your urine. If you’re properly hydrated, you should be able to produce a large amount of light-colored, clear urine. If the urine appears dark and concentrated, you may be dehydrated.

Preventing Hyponatremia

Yes, you can drink too much water. A condition called hyponatremia can occur when hikers drink large amounts of water without replenishing electrolytes. That can cause blood sodium levels to plunge because too much salt ends up getting sweated out of the body. Hyponatremia is a potentially serious condition that can lead to seizures.

  • Replenish With Electrolytes. In addition to restoring fluids, you need to maintain your body’s proper levels of sodium, magnesium, and potassium. Salt residue on your clothing or the inside of your hat is a possible warning sign of hyponatremia. So as you rehydrate, alternate water intake with consumption of fluids with electrolytes, such as sports drinks.
  • Eat snacks with salt. Salt in foods can help restore sodium levels in the bloodstream. So in addition to drinking plenty of fluids on hot days, be sure to snack frequently on foods with salt, such as nuts, pretzels, and trail mix.

Preventing Heat Exhaustion and Heat Stroke

Hot conditions can overwhelm the body’s cooling mechanisms. Heat exhaustion results from a combination of high body temperature and dehydration. It can lead to heat stroke, which is potentially fatal.

In the event of heat stroke, it’s critical that you lower the victim’s body temperature by immersing or keeping the person wet to increase evaporative cooling. The victim needs hospital treatment as soon as possible but shouldn’t be allowed to try and hike out on his or her own.

  • Take breaks. Forget about setting any personal bests. Stop more frequently and for longer durations than you would on a cooler day.
  • Look for shade. Get out of the sun as much as you can, both on breaks and on the trail. Especially when the sun is lower in the sky, portions of the trail may be shaded by trees or slopes.

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