It was a tragic mistake. On a day that would reach 98 degrees, a Northern San Joaquin Valley businessman on his way to work forgot to take his baby daughter to day care. Distracted by work, he left her in the back seat.

The interior temperature rose to more than 130 degrees. By the time he realized his mistake it was too late to save her.

As many as 30 children die this way every year in the United States, according to a national group that urges parents not to leave their children unattended in cars.

Their motto: "Not even for a minute."

The parents of Kids 'N Cars say that even though summer hasn't officially begun, nine children already have died from the heat in 2000. In the Northern San Joaquin Valley, it's already hot enough to kill children or pets left in autos -- and higher temperatures are expected this week.

Dr. Robert Padilla of the Stanislaus County Health Services Agency said children's small bodies make them vulnerable to high temperatures.

"They absorb heat really rapidly," he said. "They have a tendency to dehydrate easily."

Some dehydrated children arrive in emergency rooms after having been left in cars when a parent went shopping.

Heat stroke can strike fast. On a 93-degree day, it can take only 20 minutes for the inside of a car to reach 125 degrees. In another 20 minutes, it could reach 140 degrees. Cracking open the window usually doesn't help because it may not let in much of a breeze.

Seizures, convulsions, brain damage and death can occur when cars become ovens.

Padilla said children who die are too young to escape the situation.

"It's the little ones, who are in car seats," he said.

According to Kids 'N Cars, some states have laws against leaving pets -- but not children -- unattended inside hot cars. Though leaving a dog in a car can get you slapped with a fine for animal cruelty, there is no law in California against leaving a child in a car. The group seeks to change that.

Lani Poblete of the National Safe Kids Campaign, headed by former U.S. Surgeon General C. Everett Koop, warns parents to take safety precautions when the temperature exceeds 80 degrees. Her advice:

• Keep cars locked at all times, even in the garage.
• Teach children not to play in cars.
• Never leave your child in an unattended car.
• Double-check to make sure all young passengers have left a car.
• Before restraining your children in a car, check the temperature of the car seat surface and safety belt buckles.
• Consider using windshield shades in the front and back windows.

The Associated Press contributed to this report.

Reprinted by permission of Modesto Bee.