Rapidly rising temperatures can turn deadly. Here's warning signs and prevention tips.

With temperatures climbing, the danger isn't just the heat but how quickly it can turn into a medical emergency.

One woman knows that firsthand after suffering heat stroke, and doctors say recognizing the warning signs can save a life.

Diana Barajas is no stranger to the heat, having been born and raised in Punta Gorda, Fla.

She travels to Atlanta often to visit her son and is a frequent visitor to Piedmont Park.

A normal workout turned into a nightmare after suffering heat stroke and losing consciousness after a run without proper hydration.

"About two months ago, I fainted after I went for a run," Barajas told CBS News Atlanta, "It was in the middle of the day, and I'm not young anymore, so I need to be careful with the heat."

Dr. Niel Winawer, professor at Emory University School of Medicine, said the body often gives warning signs before heat-related illness becomes life-threatening.

"The most common thing is profuse sweating, sweating to the point where you start to get cold and clammy skin, and then a very common feature is headache, nausea, and vomiting," said Dr. Winawer.

The best defense is preparation.

Dr. Winawer advises to drink fluids before feeling thirsty, take breaks in the shade, and if you are spending hours outside to replace the electrolytes to lose through sweat."Any sports drinks that contain electrolytes that you're going to sweat out because if you just replace it with water, you could dilute the salt in your body if you're drinking a lot of water," he said.

Then, there is a difference between heat stroke and heat exhaustion.

According to Dr. Winemar, they share the same symptoms, but heat stroke patients lose consciousness and suffer cognitive defects such as slurred speech and blurred vision.

He said elderly people and those with underlying health conditions are at the highest risk for heat stroke.

Barajas said heat stroke has not deterred her from her park exercise.

She now knows how to prepare.

"I drink plenty of water beforehand always and know when to find shade," she said.

She and Dr. Winewer said listening to your body can make all the difference in the summer heat.