How to Stay Safe During a Heat Wave: Whether You're Working, Hiking, Walking, or Running

There are few outdoor hazards more underestimated than extreme heat.

Most people prepare for rain. They pack extra layers for cold weather. They pay attention to storms.

But heat?

Too often, people assume they’ll simply “drink more water” and be fine. As if tossing one water bottle into the cup holder suddenly makes them immune to physics.

Unfortunately, heat illness does not work that way.

Every summer, thousands of people require medical treatment because their bodies cannot cool themselves fast enough. Many of them are healthy, active individuals who never expected to become victims of the weather.

Whether you’re working outside, hiking your favorite trail, training for a race, or simply taking an afternoon walk, understanding how your body responds to heat can keep an enjoyable day outdoors from becoming a medical emergency.

Heat Is More Dangerous Than Most People Realize

Your body constantly produces heat.

Normally, sweat and increased blood flow to your skin allow that heat to escape. During a heat wave, that cooling system begins to struggle.

High temperatures, direct sunlight, humidity, heavy clothing, backpacks, physical labor, and dehydration all make it harder for your body to regulate its temperature.

Eventually, your core temperature begins to rise.

That is when heat illness begins.

Who Is Most at Risk?

Anyone can experience heat illness, but certain people face a greater risk, including:

• Outdoor workers

• Hikers and backpackers

• Runners and cyclists

• Children

• Older adults

• People taking certain medications

• Individuals who are dehydrated

• Those not acclimated to hot weather

Even experienced athletes are not immune. Fitness helps, but it does not eliminate the risk.

Before You Go Outside

Preparation starts before you leave home.

Check the air temperature, Heat Index, humidity, UV Index, and air quality.

A temperature of 90°F with high humidity can place far more stress on your body than 100°F in dry air. Always check the Heat Index, not just the air temperature, since it better reflects how hot conditions may actually feel to your body.

If possible, start early in the morning and finish before the hottest part of the day. Wear light-colored, loose-fitting clothing. Choose breathable fabrics. Wear a wide-brim hat.

Apply sunscreen. Bring more water than you think you’ll need.

Future You—the sweaty, slightly grumpy version of yourself halfway through the hike—will be incredibly thankful.

Hydration Starts Before You’re Thirsty

One of the biggest misconceptions is waiting until you’re thirsty.

Thirst is a delayed warning sign.

Waiting until you’re thirsty to start drinking is a little like waiting until your gas light comes on before thinking about where the next gas station might be. Technically possible. Not exactly a winning strategy.

Aim to begin any outdoor activity already well hydrated rather than trying to catch up once you’re sweating.

Drink consistently throughout the day rather than consuming a large amount all at once.

For longer hikes, physically demanding work, or endurance activities lasting more than an hour, consider replacing electrolytes, not just water.

Sweat removes sodium, potassium, and other minerals your muscles and nervous system rely on.

Too much plain water without replacing electrolytes can also become dangerous during prolonged activity.

Know the Warning Signs

Heat illness can happen in stages.

Heat Cramps

Heat cramps are often one of the earliest warning signs. Symptoms may include painful muscle cramps, heavy sweating, and fatigue.

Stop activity, move to a cooler place, hydrate, and replace electrolytes.

Heat Exhaustion

Heat exhaustion means your body is struggling to keep up. Symptoms may include heavy sweating, weakness, headache, dizziness, nausea, rapid pulse, and cool, clammy skin.

Move into shade or air conditioning immediately.

Drink fluids if you are able. Cool the body using wet towels, cool water, or fans. Rest. Do not continue exercising or working through it.

Heat Stroke

Heat stroke is a medical emergency.

Symptoms may include confusion, slurred speech, loss of consciousness, hot skin, a core temperature above 104°F, and seizures. Skin may be dry, but it can also still be sweaty.

Call emergency services immediately. Begin aggressive cooling while waiting for help.

Do not give fluids to someone who is unconscious or unable to safely swallow.

Heat stroke can become fatal without rapid treatment.

The Six Sources of Heat Stress

When people think about hot weather, they usually focus on the air temperature. In reality, your body is responding to several sources of heat at the same time.

Air Temperature — The surrounding air sets the baseline, but it is only one part of the equation.

Direct Sunlight — Sunshine adds heat directly to your body, making you feel much hotter than the air temperature alone suggests.

Radiant Heat from the Ground — Asphalt, concrete, gravel, rock, and sand absorb the sun’s energy and radiate that heat back toward you.

Humidity — High humidity slows the evaporation of sweat, reducing your body’s ability to cool itself.

Wind, or Lack of It — Even a light breeze helps remove heat from your skin, while still air makes it much harder to cool down.

Your Own Body Heat — Every step, climb, shovel of dirt, or mile you run generates internal heat that your body must also release.

Together, these six factors determine how much heat stress your body experiences, not just the number on the thermometer.

It’s Not Just the Air Temperature

When most people check the weather, they look at one number: the air temperature.

But your body experiences much more than that.

The sun shining overhead is only one source of heat. The ground beneath your feet can also absorb, store, and radiate energy back toward your body, increasing the amount of heat you are exposed to throughout the day.

This is known as radiant heat, and it can make two outdoor activities feel completely different even if the air temperature is exactly the same.

I have noticed this on my own morning runs. Most of my route follows shaded pavement and quieter roads, but there is one stretch, less than half a mile, along a gravel and dirt road. Every time I reach that section, I can physically feel the heat surrounding me. It is not just coming from the sun above. It is rising from the ground below as well.

Turns out the ground can quietly store solar energy all morning like it is charging up for its villain arc.

Different surfaces absorb and release heat differently.

Asphalt can become much hotter than the surrounding air and continue radiating heat long after the sun begins to set.

Concrete stores heat throughout the day, making sidewalks, parking lots, and urban areas feel much warmer than nearby parks.

Gravel and rocky trails absorb and reflect sunlight while also radiating stored heat, increasing the stress on your body.

Bare rock, especially on exposed overlooks and mountain ridges, can become surprisingly hot during the afternoon.

Sand often becomes hot enough to burn bare feet on sunny days.

Grass, forest soil, and shaded trails generally remain much cooler because vegetation blocks direct sunlight and moisture helps dissipate heat.

This is one reason why an afternoon hike through an open field may feel significantly harder than a shaded forest trail, even though the thermometer has not changed.

The air temperature tells only part of the story.

The surface beneath you, the amount of shade available, humidity, wind, and even the color of your clothing all influence how much heat your body must manage.

When planning time outdoors during a heat wave, do not just ask, “How hot is it?”

Ask yourself, “How much heat is my body actually being exposed to?”

That simple shift in awareness can help you make better decisions about your route, your pace, your hydration, and when it is time to seek shade.

Tips for Hikers

Trails often become hotter than nearby towns.

Rock surfaces, exposed ridges, and limited shade can dramatically increase heat exposure.

When hiking in hot weather, start at sunrise if possible. Know where water sources are.

Carry more water than expected. Rest in the shade frequently. Slow your pace. Turn around if conditions worsen.

Water weighs a lot less than an ambulance ride. Just saying.

No summit, scenic overlook, or “but I already came this far” moment is worth risking your health.

Tips for Outdoor Workers

Construction crews, landscapers, maintenance workers, road crews, and outdoor staff often cannot avoid the heat entirely.

Reduce risk by taking scheduled cooling breaks, rotating physically demanding tasks, drinking water regularly, wearing cooling towels if appropriate, using shade whenever available, and watching coworkers for signs of heat illness.

One important reality is that people suffering from heat illness often do not recognize it in themselves. Your coworkers may notice changes before you do.

Confusion, irritability, poor coordination, unusual fatigue, or acting “off” can all be warning signs.

Tips for Walkers and Runners

Many runners pride themselves on pushing through discomfort.

Heat is one situation where backing off is the smarter decision.

There is a difference between mental toughness and arguing with your body’s cooling system. One builds resilience. The other usually ends with regret.

During a heat wave, reduce your pace. Shorten your distance. Walk more often. Choose shaded routes. Wear breathable clothing. Carry water. Stop if you feel dizzy, nauseated, unusually weak, or mentally foggy.

Fitness improves performance.

It does not make you heatproof.

Acclimation Matters

Your body adapts surprisingly well to heat, but it takes time.

Over one to two weeks of gradual exposure, your body becomes more efficient at cooling itself.

You sweat earlier. You conserve electrolytes more effectively. Your heart does not have to work quite as hard.

The mistake many people make is expecting Day One performance in Day One heat.

Your body is not being dramatic. It is basically saying, “Hey, maybe let’s not pretend we are already adapted to living on the surface of the sun.”

Build into hot weather gradually.

The body can lose much of its heat acclimation after a week or two away from hot conditions, so returning to the heat may require another gradual adjustment.

Nature’s Lesson

The outdoors constantly reminds us that resilience is not about ignoring conditions.

It is about adapting to them.

Strong hikers adjust their pace.

Experienced workers take breaks.

Smart runners know when to slow down.

Nature does not hand out bonus points for stubbornness. It rewards awareness, preparation, and adaptability.

The goal is not simply finishing the trail, completing the shift, or reaching your mileage goal.

The goal is making it home safely so you can enjoy another day outside tomorrow.

Understanding heat stress is crucial for anyone who spends time outdoors.

Heat is not just uncomfortable. It places real stress on the body, especially when temperature, humidity, direct sun, radiant heat, still air, and physical effort all combine.

By checking conditions, starting hydrated, replacing electrolytes when needed, recognizing warning signs, and adjusting your pace, you give your body a much better chance of keeping up.

The elements are not just challenges. They are teachers.

Heat teaches awareness.

It teaches preparation.

And occasionally, it teaches us that the smarter choice is shade, water, and calling it a day before the sun turns the trail into a toaster oven.