The Deadliest Summer Danger
Heat is the deadliest weather event — killing an average of 658 people in the United States every year, according to a study of heat deaths from 1999 to 2009, released by the U.S. Centers for Disease Control and Prevention.
But these deaths are preventable, the agency said, as long as proper safety steps are taken.
"In the heat, make sure you're checking in on elderly neighbors, friends or family that may be in the high-risk category [for heatstroke] to make sure that they are taking care and not having any problems," Theresa Lash-Ritter, M.D., the medical director of the urgent and express care clinic at Cleveland Clinic, told weather.com.
For more on what to look for — and when you're most in danger — read on.
NEXT: How hot is too hot?
It Can Strike When It's Not That Hot
Heatstroke might conjure images of 105-degree days. But the reality is, the dangers start at a much lower temperature.
"We tell people 'over 80 degrees and over 75-percent humidity,'" Dr. Lash-Ritter said of heatstroke dangers. "Especially if you are going to be in direct sunlight, [for example] working construction, or in any area where it's not shaded, that is [the most dangerous]."
How much heat can hurt largely depends on how acclimated you are to sweltering temperatures, she added.
NEXT: Who is at risk?
It's a Danger for Seniors and Children
"People at risk are older people over the age of 65; younger children under the age of 5; people with chronic illnesses; people who are overweight and those not acclimated to being in heat," Dr. Lash-Ritter said. "So when you look at who is at risk that's a huge number of people, as the weather warms up in the summer."
So far this year, 17 children have died as a result of heatstroke in a hot car, a terrifying example of the power of hot weather.
Outdoor exercisers should watch out for steamy days, too. Dr. Lash-Ritter suggested athletes make sure they are well hydrated before leaving the house, and that they wear loose-fitting, light-colored clothing and carry fluids with them.
NEXT: An early heat-stroke sign
Heatstroke Can Be a Headache
When you're suffering from heatstroke, one of the first symptoms is a headache or feeling of lightheadedness, Dr. Lash-Ritter said.
These are both signs you need to seek shade, and drink water in an effort to cool your body down.
Muscle cramps in the legs or abdomen are another hallmark sign of early heatstroke.
NEXT: Stomach symptoms
You Can Get Sick to Your Stomach
Nausea and vomiting are both early heatstroke symptoms, Dr. Lash-Ritter said. If you don't recognize what is going on, and get yourself into a cooler environment, some of heatstroke's life-threatening complications may be up next.
NEXT: Monitor sweat
When You Stop Sweating, Problems Start
In older people who end up with heatstroke because of a hot house, for example, Dr. Lash-Ritter said they are likely to stop sweating. "Their skin is very dry and hot," she explained, "whereas if it's [heatstroke from] exertion, you will have moist skin and be sweating."
Outdoor exercisers should watch for a change in their sweating pattern as a sign of trouble, but likely, their skin will continue to feel moist after heatstroke strikes. "You can get 'the hot chills' where you're very hot and exerting yourself, but all of a sudden you feel chilled. That's the point where you're getting a problem," Dr. Lash-Ritter said.
NEXT: When to call 911
Confused? Call for Help
If you've felt early heatstroke signs — lightheadedness, nausea, cramps — and haven't been able to get your body's temperature under control, your symptoms are likely to progress.
Confusion and agitation are two signs that your life could be in danger. "The second there is any kind of confusion or agitation, you need to call 911 as an emergency," Dr. Lash-Ritter said.
If you are caring for someone with potentially deadly heatstroke symptoms, cooling them off should be your top priority. Move them into shade or air conditioning, apply damp towels or a fan, and help rehydrate the person with water, the Mayo Clinic suggests. In an outdoor emergency, soaking in a cool pond or stream can help.
But "home treatment isn't sufficient for heatstroke," the Mayo Clinic website warns. "Seek emergency medical help."
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