Excessive heat warning continues

The warning, which was initially expected to kick in at 7 a.m., was already in effect before 6 a.m. It means those who are outside for an extended period of time need to be very careful, and it is important for those who do not have air conditioning to try and keep cool. Summer heat waves can be deadly.

Approximately 40 percent of heat-related deaths occur in people 65 and older. However, the heat can also kill healthy, young people usually because, doctors say, they often do not recognize their limits or the dangers of exercising in hot weather, for example, especially combined with high humidity.

A stretch of dangerously high temperatures is ahead, according to ABC7 meteorologist Tracy Butler. Some heat index readings could reach 110 degrees. However, simple steps can prevent serious health problems.

Staff at Chicago-area hospitals say they are prepared to see an increase in cases of heat-related illness Wednesday.

"We have cool, IV fluids always available. We have misters available and fans. And we also have cooling blankets available for our patients who are really ill and have heat stroke," said emergency medicine Dr. Tarlan Hedayati of Stroger Hospital.

Dr. Hedayati also explained the symptoms of heat stroke to look out for.

"Heat stroke is a spectrum of disease. It can start off with just heat exhaustion, nausea, vomiting, headaches, dizziness, and then it escalates as the body has difficulty getting rid of that heat, the body temperature rises, can exceed 103 degrees. And then you initially start off sweating, and then the body loses its ability to sweat, and so patients can become confused and may become unconscious and that can lead to death," she said.

The excessive heat warning will last through Friday morning. Dr. Hedayati offered the following tips for coping with the high temperatures: