HELOTES, Texas >> A 7-month-old boy died Friday after being left all day in a hot sport utility vehicle in a San Antonio-area Wal-Mart parking lot.

The child’s father is employed at the store in Helotes, a San Antonio suburb, and told officers that he forgot to drop the child off at day care before going to work about 6:15 a.m., said Helotes police Capt. Anthony Burges. When the father finished work and returned to the SUV about 3 p.m., he found his child dead. The father was taken to a hospital after reporting chest pains, Burges said.

No charges have been filed, and the identities of the father and boy have not been released.

Temperatures in the area hovered around 100 degrees much of the afternoon.

The death brings the toll of children dying in hot cars this year to at least 27, six in Texas, said Janette Fennell, founder and president of KidsAndCars.org, a national child safety nonprofit based in Philadelphia. On Aug. 4, twin 15-month-old girls died after being found in the back seat of a hot SUV parked in front of a duplex car Carrollton in northwestern Georgia. When police arrived, they found people holding the girls in the water of a baby pool behind the duplex, some with ice packs, trying to cool the girls off.

Last year, there were 15 heatstroke deaths of children in vehicles, Fennell said.

The toll began rising sharply in the 1990s with the passing of laws requiring that young children be placed in the back seat to avoid air-bag injuries. With the children strapped into the back seat, drivers can tend to forget them, Fennell said.

Fennell said the numbers of heatstroke deaths of kids in cars fluctuated in the following decades, averaging 37 such deaths a year since 1998. The worst year was 2010, with 49, according to both a count by Fennell and Jan Null, a research meteorologist at San Jose State University, who also tracks numbers.

The temperature inside a parked car on a 90-degree day will reach 119 degrees in 20 minutes and 133 degrees after an hour, Null said.

Parents should get into the habit of always opening their back doors when they leave the vehicle, according to Fennell. Leaving a purse or cellphone in the back seat can help. Other strategies include keeping a stuffed animal in the car seat and placing it in the front seat when the child is strapped in as a reminder that the child is there. Parents also need to make sure their day care calls them if the child doesn’t show up, she said.