With temperatures approaching 100 degrees the next couple of days, the risks of overheating rises exponentially — especially for small children in cars.

The temperature in a car can rise “20 degrees in 10 minutes” on a regular sunny day, said Dr. Michelle Macy, pediatric emergency room physician at the Ann & Robert H. Lurie Children’s Hospital.

But with the heat index hitting as high as 110 degrees this weekend, the risks are even greater.

“Young children will heat up three to five times faster than you and I will,” said Macy.

There have already been 21 children who have died from heatstroke in cars nationally this year, she said. Last year, there were 52 deaths. In Illinois, there have been 20 since 1998, or about 1 per year.

The vehicular heatstroke deaths Macy has seen are from children being left behind in the car by parents, even for “just 10 minutes,” and children sneaking into cars.

In addition to deaths, hot temperatures also pose potential kidney and brain injuries to children.

“Due to [children’s] body shape and size, they aren’t able to dissipate that heat like an adult body would,” said Macy.

When a child’s body overheats, “sensitive” parts of the brain responsible for consciousness become affected. A child’s muscles can also become “irritated and inflamed,” resulting in the release of chemicals that can clog and ultimately cause their kidneys to “shut down.”

Add dehydration, and the health risk becomes even more severe and injuries can be debilitating and permanent.

What is crucial, Macy stressed, is parental mindfulness. Adults should always check the backseat before leaving a car and even set reminders to do so.

Adults who see children alone in cars should call 911 and then try to find the driver.

Getting any child left in a car into a cool area, placing cool towels on them and placing ice in their armpits can be the steps that save them from death, she said.

The National Weather Service put out an excessive heat warning for Friday and Saturday, when said temperatures could reach 98 degrees each day.

The last time Chicago saw temperatures greater than 100 degrees was three consecutive days from July 4, 2012, according to data from the National Weather Service.