What leads to heat stroke?

During summer in the U.S., temperatures often exceed 100 degrees Fahrenheit (38 degrees Celsius), turning heat stroke into a serious concern. This condition can be deadly because it strikes swiftly, leaving little time for a response.

Imagine it's a scorching 100°F outside. The human body aims to maintain a temperature of 98.6°F. The only way to achieve this is by sweating. By releasing moisture onto the skin and allowing it to evaporate, your body can effectively cool itself and stay within the ideal temperature range.

Sweat is an effective cooling mechanism as long as your body has enough water — after all, it takes water to produce sweat. If you run low on water, sweat production stops, and your body overheats quickly. It's surprisingly easy to run out of water, as the body can generate up to 0.5 gallons (2 liters) of sweat per hour in hot conditions. Unless you're drinking at the same rate, dehydration will set in, and sweat will cease. Your body's thirst response often isn't enough to keep up with your needs, and it's commonly said that by the time you feel thirsty, dehydration has already begun. Therefore, constant hydration is key, even if you don't feel thirsty.

Another factor that can contribute to heat stroke is extremely high humidity, which prevents sweat from evaporating and cooling the body.

Whether it's due to insufficient sweating or an inability to evaporate it, your body's core temperature can rise dangerously fast in hot weather. Once your core hits 106 degrees F, things become critical. Warning signs include flushed, hot, dry skin (as the body dilates skin blood vessels to release heat, causing the skin to appear red, and the dryness comes from a lack of sweat), an accelerated heart rate, dizziness, and confusion. The latter two symptoms occur because the high body temperature affects the brain.

For children and pets, heat stroke can strike unexpectedly, particularly in a hot car or a stuffy room. Cars are especially risky. At Mytour, we conducted the following experiment:

Within just 15 minutes, the temperature inside the car reached 110 degrees F, a level that can quickly become fatal.

The rapid rise in temperature is due to a car's ability to act like a solar oven, harnessing the greenhouse effect to trap heat. Sunlight heats the car’s metal body, and it streams in through the windows to warm the inside. Glass is transparent to visible light, but blocks infrared light — the heat that attempts to escape. As a result, the temperature climbs rapidly, often making it impossible to touch the steering wheel without burning your hand. Cracking the window won’t help either. It’s never safe to leave a child or pet in a parked car, even for a short time.

The only way to treat heat stroke is to cool the person down. Here’s how you can help:

Without treatment, heat stroke can be fatal in under an hour.