Summer will open up with extreme heat. Here's how you can avoid heat-related illness.

BALTIMORE - Summer will welcome Maryland this week with dangerous heat and humidity.

With the rising temperatures come the risk of heat exhaustion and heat stroke.

Summer officially begins on Thursday, and temperatures are expected to be in the mid-90s to 100 degrees by next weekend.

Dr. Omoyemi Adebayo, a physician at the University of Baltimore Washington Medical Center, explains that prolonged exposure to extreme temperatures can be a real health threat, especially for older people and young children.

Look out for these symptoms 

"Kind of starts out as maybe a fatigue, a little bit of cramps in the legs," Adebayo said. "Sometimes patients will express excessive thirst and this can progress to the more moderate forms. When you start to get into what is called heat exhaustion, and that is when patients will actually experience headaches, sometimes nausea, vomiting, and then, as it progresses even further, patients may complain of chest pain. They may complain of confusion, or bystanders may notice that they are confused, and they can progress into the most extreme form in terms of complete loss of consciousness, cardiac arrest and death, in the worst case."

Preparation is key. Take these precautions 

"You wanna make sure that you're dressed appropriately for the weather," Adebayo said. "That means wearing light-colored, light-fitting clothing, ideally something that may be like jersey fit or jersey knit material that is very breathable. You wanna pack plenty of water for yourself as well. And although sunscreen doesn't protect you per se from heat exhaustion or heat stroke, you definitely wanna protect your skin as well."

If you or a person you know is experiencing heat-related illness, move to a cooler location, apply wet cloths to the body and drink water.

If the person vomits or refuses to drink, call 911 as heat exhaustion can lead to heat stroke.