Never Leave Children, Disabled Adults or Pets in Parked Vehicles

Each year, dozens of children and untold numbers of pets left in parked vehicles die from hyperthermia. Hyperthermia is an acute condition that occurs when the body absorbs more heat than it can handle. Hyperthermia can occur even on a mild day. Studies have shown that the temperature inside a parked vehicle can rapidly rise to a dangerous level for children, pets and even adults. Leaving the windows slightly open does not significantly decrease the heating rate. The effects can be more severe on children because their bodies warm at a faster rate than adults.

Courtesy of San Francisco State University. Use of this graph does not imply NWS endorsement of services provided by San Francisco State University.

How Fast Can the Sun Heat a Car?

The sun's shortwave radiation (yellow in figure below) heats objects that it strikes. For example, a dark dashboard or seat can easily reach temperatures in the range of 180 to over 200°F. These objects (e.g., dashboard, steering wheel, child seat) heat the adjacent air by conduction and convection and also give off longwave radiation (red in figure below) which is very efficient at warming the air trapped inside a vehicle.

Shown below are time lapse photos of thermometer readings in a car over a period of less than an hour. As the animation shows, in just over 2 minutes the car went from a safe temperature to an unsafe temperature of 94.3°F. This demonstration shows just how quickly a vehicle can become a death trap for a child.

Objects Heated by the Sun Warm Vehicle's Air

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Animation Courtesy of General Motors and San Francisco State University. Use of this animation does not imply NWS endorsement of services provided by General Motors and San Francisco State University.
Hyperthermia deaths aren't confined to summer months. They also happen during the spring and fall. Below are some examples.

The atmosphere and the windows of a car are relatively transparent to the sun’s shortwave radiation yellow in figure below) and are warmed little. This shortwave energy, however, does heat objects it strikes. For example, a dark dashboard or seat can easily reach temperatures in the range of 180°F to more than 200°F. These objects, e.g., dashboard, steering wheel, childseat, heat the adjacent air by conduction and convection and give off longwave radiation (infrared), which efficiently warms the air trapped inside a vehicle. Learn more about excessive heat and cars.

Vehicle Related Heat Deaths

Honolulu, HI, March 07, 2007: A 3-year-old girl died when the father left her in a child seat for 1.5 hours while he visited friends in a Waikiki apartment building. The outside temperature was only 81 degrees.
North Augusta, SC, April 2006: A mother left her a 15-month-old son in a car. He was in a car for 9 hours while his mom went to work. She is now serving a 20-year prison sentence.
Greenville, TX, December 01, 2012: A 6-month-old boy died after being left in a car for more than 2 hours by his mother. She was charged with murder. The temperature rose to an unseasonably warm 81 degrees on that day.
Adults are in danger too. On July 12, 2001, a man died of heat stroke after falling asleep in his car with the windows rolled up in the parking lot of a supermarket in Hinds County, MS.

Safety Tips for Concerning Children

Make sure your child's safety seat and safety belt buckles aren't too hot before securing your child in a safety restraint system, especially when your car has been parked in the heat.
Never leave your child unattended in a vehicle, even with the windows down.
Teach children not to play in, on, or around cars.
Always lock car doors and trunks--even at home--and keep keys out of children's reach.
Always make sure all children have left the car when you reach your destination. Don't leave sleeping infants in the car ever

Downloadable Child Vehicular Heat Stroke Prevention Logos