Why Is Hot Weather So Dangerous?

When the temperature climbs, your body is built to work overtime to keep you cool, but there’s a limit to what it can handle.

According to family physician Dr. Allison Edwards, “hot weather actually can be quite damaging to your health and can be pretty scary.”

Heat-related illness can range from mild exhaustion to something much more serious, and she warns, it can sneak up on you faster than you expect.

“It can happen kind of insidiously where you don't feel it coming on,” Dr. Edwards explains. That’s why it’s important to check in with yourself, and with others, when you’re outside in the heat.

What You Should Know

For starters, your body’s main cooling system is sweat. “If you are sweating, that's good,” she says.

Sweat cools your body as it evaporates off your skin. But in very hot or humid conditions, that system can fail.

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“At a certain point it just becomes ineffective. So once you get up above the high 90s, you're not going to lose enough temperature through sweating,” warns Dr. Edwards.

Some people are more vulnerable than others. “Those who need to be extra careful in high heat are the very young and the very old. On both sides of that spectrum, it's just harder to regulate your temperature, harder to sweat,” Dr. Edwards says.

People with disabilities, limited mobility or who are pregnant also face higher risks.

Warning Signs To Watch For

Feeling thirsty? That’s your first clue. “If you feel thirsty, you should drink water,” Dr. Edwards advises, noting that plain water (sans electrolytes) is enough for most people.

(MORE: What Meteorologists Want You To Know About Heat)

As your exposure to heat progresses, symptoms can escalate. Heat exhaustion may include dizziness, confusion, nausea or vomiting.

If things get worse, it can turn into heat stroke, which is a a life-threatening emergency. “50 to 80% of people who have heat stroke will end up dying from it,” Edwards warns.

What To Do Next

Unfortunately, Dr. Edwards explains, there’s no golden rule or strict time limit for being outside in the heat.

“You have to listen to your body,” she says. If you feel dizzy, weak, or overly tired, it’s time to go inside.

Once you do, cool down quickly: by getting into air conditioning, shedding layers of clothing, drinking ice water and allowing air to circulate around your body. And if symptoms don’t improve or get worse, don’t wait until it's too late, seek medical help immediately.

weather.com lead editor Jenn Jordan explores how weather and climate weave through our daily lives, shape our routines and leave lasting impacts on our communities.