What to Eat and Drink While Hiking in Hot Weather

By Briana Bruinooge, RD, CSSD, CPT & Aaron Owens Mayhew, MS, RDN, CD

Updated January 3, 2024
This post may contain affiliate links.
Three hikers hiking on a hot weather while packing foods to eat on hot days.

Whether you’re climbing a peak or enjoying an easy day hike, hiking in hot weather can be tricky. Knowing which foods to eat on hot days can make a significant impact on how your adventure plays out. High temperatures can also negatively affect your athletic performance and put you at risk for heat illness. Knowing the risks of heat illness and how to prevent them will keep you adventuring all summer safely long. It can be as simple as staying hydrated and choosing the right foods to eat on hot days.

Fluid loss and impaired performance

Eating and drinking properly throughout the day is essential in hot weather to avoid heat illness and decreased performance. If you don’t, your muscle strength could decrease while you’re nearing the summit of your climb. Your athletic performance starts to suffer when your body loses just 2-3% of its weight in fluids. For an athlete weighing 200 pounds, 2 percent body weight would be 4 pounds, or two liters in fluid. Typical Nalgene bottles are one liter each. Losing this much sweat during hot weather activities is not difficult. You need to replace fluids frequently to stay hydrated. If the hot weather is also windy, humid, or dry, water and electrolyte needs are increased even more.


Loss of electrolytes while hiking in hot weather

You’ve probably noticed that you lose more fluids in hot weather. We sweat more when it’s hot because sweating helps to cool our bodies down. But did you know that you also lose more electrolytes in the heat? Electrolytes are essential for your body to function, and we lose them in sweat.

The main electrolyte in sweat is salt (sodium chloride). In addition to salt, sweat contains small amounts of potassium, magnesium, and calcium. We need to replace all of these electrolytes as we’re hiking.

Fluid and electrolyte losses vary widely depending on the person. Some athletes are “salty” sweaters or sweat more than others.

If you lost 2 pounds of fluid weight (one liter) mostly from sweating, you could lose:
  • 500-1800 mg Sodium & 700-2800 mg Chloride = almost a teaspoon of salt at the higher end
  • 150-400 mg Potassium = 2 oranges
  • 0-35 mg Magnesium = 1 fig
  • 0-120 mg Calcium = 1/3 cup almonds

Heavy sweaters, especially when hiking in hot weather, could lose up to three liters of fluid every hour, depending on the activity. That adds up to a lot of electrolytes lost! Salt is the most important one to replace. Luckily, electrolytes are widely available in common trail foods such as dried fruits, nuts, seeds, and salty snacks like pretzels. Commercial rehydration mixes are also available but are usually unnecessary if you eat a variety of salty snacks throughout the day.

Risk of hyponatremia

Let’s say you’re hiking in Moab, Utah, in June. It’s 98 degrees Fahrenheit, but somehow you don’t feel a drop of sweat. Here’s something to remember in dry heat (desert): we don’t always notice how much we sweat because it evaporates so quickly. Compare this to New England’s humid summers, where you might be sweating buckets. With high humidity, sweat doesn’t evaporate into the air as easily because the air is already full of water. Both conditions require extra sweat to cool the body down.

If you’ve been sweating all day and drinking four Nalgenes of plain water, you might notice that you have a headache and feel bloated, puffy, and nauseous. You may even experience vomiting and confusion. These are symptoms of hyponatremia, a condition that occurs seen when sodium levels drop below 130 mmol/L. What happened? You essentially diluted your blood with too much water.

To avoid hyponatremia and dehydration, consume fluids and food sources that contain sodium, especially when hiking for longer than one hour. Also, plan ahead to have fluids available to sip all day long. You should never get so thirsty that you feel the need to drink all four of those Nalgenes at once!

Compare a few of the common electrolyte replacement drinks available in our shop

gnarly nutrition hydrate raspberry 86 cal oz

250 mg Sodium, 100 mg Potassium, 80 mg Magnesium (per packet)

nuun sport hydration strawberry lemonade

300 mg Sodium, 150 mg Potassium, 55 mg Magnesium (per tablet)

gatorade lemon lime singles 106 cal oz

230 mg Sodium, 70 mg Potassium, 0 mg Calcium (per packet)

Foods to eat on hot days

Here’s a list of hiking-friendly snacks listed by electrolytes:
  • Salt (sodium chloride) = salted nuts, trail mix, pretzels, crackers, popcorn, pickles, and jerky
  • Potassium = bananas, melons, oranges, grapefruit juice, and kiwis
  • Magnesium = pumpkin seeds, figs, cashews, and peanuts
  • Calcium = almonds, cheese, dry milk, fortified cereals

Check out some of our favorite electrolyte replacement snacks in our shop

madi ks roasted salted almonds

190 mg Sodium, 380 mg Potassium, 154 mg Magnesium (per packet)

pretzel crisps 3 oz 110 cal oz

830 mg Sodium, 90 mg Potassium, 0 mg Calcium (per packet)

samai plantain chips 160 cal oz

188 mg Sodium, 325 mg Potassium, 0 mg Calcium (per packet)

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Tips for avoiding heat illness while hiking in hot weather

Symptoms of heat illness include dizziness, headaches, cramps, muscle spasms, nausea, and vomiting.

To avoid dehydration and heat illness, make sure to:
  • Adapt to hiking in the heat, which takes seven to fourteen days.
  • Start with shorter hikes in the heat, and gradually increase exercise time daily.
  • Begin hiking well hydrated. Check your urine color to see if you’re on the right track. Urine should be light yellow to nearly clear. If it’s dark yellow, you must drink more before starting hard exercise in the heat.
  • Consume cold fluids during and after hiking. Flavoring your fluids may make you more likely to keep sipping. Hydro Flasks are awesome re-usable water bottles that keep fluids cold for hours.
  • Make a ‘mocktail’. Add some frozen blueberries, squeezed lemon wedges, a dash of salt, and slapped mint for a delicious flavor and extra electrolytes. Make sure you literally slap the mint with your hands so the oils extract!

Heat can kill your appetite, but it’s important to still have the right foods to eat on hot days and fluids before, during, and after your hike. Optimal hydration requires a balance of water, electrolytes, and carbohydrates. Seek out a Sports Dietitian to individualize your nutrition needs and fitness goals!

Disclaimer: This is general nutrition advice, and you should talk with your physician before implementing any dietary or lifestyle changes. 

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    Backcountry Foodie What to Eat and Drink in Hot Weather blogger and dietitian nutritionist Briana Bruinooge

    Briana Bruinooge, RD, CSSD, CPT is a board Certified Specialist in Sports Dietetics (CSSD). She works closely with teenage and above adults to match nutrition intake with optimal athletic performance. Briana enjoys trail running, gravel biking, and hiking and skiing in the White Mountains of New Hampshire. Her longest trail run has been a 50K in Maine. She understands that matching athletic performance with nutrition needs is not an easy task, and she is here to help. Check her out at nenutritionexercise.com

    Backcountry Foodie Aaron Owens Mayhew with her dog Ella

    Aaron Owens Mayhew, MS, RDN, CD, is a registered dietitian and ultralight long-distance backpacker with over 20 years of nutrition and backpacking experience. She’s also the founder and owner of Backcountry Foodie, an online ultralight recipes and meal planning platform for backpackers. She also enjoys teaching hikers about backpacking nutrition via virtual masterclassesYouTube videos, and podcast episodes. You can follow Aaron’s adventures in the kitchen and the backcountry via Instagram and Facebook.

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