How hot does a car get in the sun? Here's why heat can be so deadly in a parked car.

The heat taking over much of the U.S. was nearly deadly for a baby in South Texas, with a viral video showing people having to break through the car's windshield to save him after he was accidentally locked inside with the keys. While the baby was saved and is believed to be OK, the incident is highlighting just how catastrophic extreme heat can be in parked vehicles. 

Extreme heat is the No. 1 weather-related killer in the U.S. Even when temperatures outside seem relatively low compared with what's been experienced in recent weeks, parked vehicles essentially become ovens under the sun's rays. 

So, how hot can a car get in the sun? All it takes is an 80-degree Fahrenheit day to bring the normal car temperature to triple digits.