It's a nightmare scenario for any parent: a child gets left in a car on a hot day. By the time someone notices, the temperature in the car has climbed and the child dies from heat stroke.

Courtesy of The National Highway Traffic Safety Administration

According to Jan Null, a Certified Consulting Meteorologist at San Francisco State University, so far in 2013, 23 children in the U.S. have died of heat stroke as a result of being left in cars. The vast majority of cases tend to happen in southern states, but as heat waves affect the entire country, even northern states are seeing cases of children dying after being left in a hot car.

Kids and Cars, a safety advocacy group, reports that on average, 38 children die each year after being trapped in hot cars. While Kids and Cars stresses that forgetting a child in a car on a hot day can happen to anyone, risk factors for parents include stress, lack of sleep, a change in routine and distractions. Infants and young toddlers, who ride in rear-facing car seats and who often fall asleep in cars, are at high risk for being left in cars, says Kids and Cars, since they are likely to be quiet and hard to see from the driver's seat.

[Read Four Keys to Keeping Kids Safe in Cars]

Measures like leaving the car's windows down a little bit are unlikely to keep a car from heating to dangerous levels. According to Null's research, on an 80-degree day, the temperature inside a car can reach 109 degrees in 20 minutes. In 60 minutes on an 80-degree day, the temperature inside a car can reach 123 degrees.

Surface temperatures in a car can get even hotter. According to the National Weather Service, dark surfaces in a car, like a dashboard or child's car seat, can reach 180 to 200 degrees.

Courtesy General Motors

There are steps that parents can take to prevent these tragedies. Put an object you'd notice if you forgot, like your purse, wallet or cell phone, in the rear seat so you're forced to check the area before leaving the car. The National Highway Traffic Safety Administration has a "Look Before You Lock" campaign aimed at reminding parents to check that there is no one in the car before they lock it.  

While experts have public service campaigns full of tips for preventing heat stroke in cars, sometimes the most helpful advice comes from real-life parents. What do you do to keep your kids safe around cars in the summertime?

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