Officials in the United States reveal that an average of 38 children have died every year between 1998 and 2013 due to heatstroke after their parents left them in parked cars in the blazing heat of summer, with majority of the children under the age of five years.
And so far this year, the toll stands at 17, prompting a national campaign urging parents and caregivers never to leave kids alone in parked cars.
"Every summer it seems that we live out the same nightmare," said Transportation Secretary Anthony Foxx, a father of two, at Thursday's launch of the "Where's Baby? Look Before You Lock" drive.
To make the point, thermometers fitted to a dark green Chevrolet Cruze sedan at the launch in Washington showed 78.3 degrees (25.7 Celsius) outside, but 96.1 degrees (35.6 Celsius) inside -- and that, on an overcast day.
Twenty-nine percent of children who die of heat stroke in cars got into the vehicle by themselves -- but in another 52 percent of cases, they were simply left behind by forgetful adults, the National Highway Traffic Safety Administration (NHTSA) said.
Young children are particularly vulnerable because their body temperature can rise three to five times faster than an adult's, said pediatrician Leticia Manning Ryan of the Johns Hopkins Children's Center in Baltimore, Maryland.
"When a child's internal temperature gets to 104 degrees (40 Celsius), major organs start to shut down -- and when that child's temperature reaches 107 (41.7 Celsius), the child can die," she said.
More often than not, children are forgotten in cars because stressed-out parents and caregivers suffer memory lapses, Foxx said.
"Based on the data we have, often, it's being fatigued and overwhelmed that leads to these kinds of tragedies," he said.
Tragic tales of children -- many of them buckled into special child seats that are mandatory on US roads -- are a regular summer fixture of US news coverage.
In this year's most sensational case, a Georgia man left his 22-month-old son inside a sweltering hot SUV outside the Home Depot store where he worked.
At his ongoing murder trial, police alleged that the father, Justin Ross Harris, 33, was more interested in "sexting" a teenaged girl than caring for the welfare of his baby Cooper.
In a online survey, 11 percent of American parents -- two-thirds of them men -- admitted to having left a child locked inside a parked car by mistake.
That represents more than 1.5 million parents, said Public Opinion Strategies, which conducted the study at the start of the year.
At Thursday's campaign launch, Reginald McKinnon painfully recalled the day he took his 17-month-old to a doctor's appointment, then rushed to his telecoms job in Florida -- forgetting to drop her off at the nursery.
"To my horror, I realized (upon returning to the vehicle at the end of the working day) that Peyton was still in her car seat," he said. "I heard someone screaming -- it was me."
Two years ago, NHTSA studied three devices which claim to detect the presence of young children in locked cars, but concluded that their performance fell short of satisfactory.
More than 5,800 people have signed an online petition launched by KidsAndCars.org, an advocacy group, urging President Barack Obama to fund more research into such devices.
"Sadly, the technology is not there yet," said NHTSA acting administrator David Friedman on Thursday.
Until it is, adults are advised to put something they'd instinctively reach for at the end of a car journey -- like a mobile phone, a laptop or handbag -- right next to their child, and never to let youngsters play in a parked vehicle.
And should anyone happen upon a child alone in a locked car, Foxx said, they should immediately call the police or firefighters. Or smash the window.