This month, CHP officers like Jeanie Hoatson are tying purple ribbons on the antennas of their patrol cars. The ribbons are intended to remind people - it's illegal in California to leave a child six-years-old or younger in a vehicle alone.
"We get asked often times what the purple ribbons mean - because not many people are as aware as we would hope."
Researchers say - every year, about 40 kids die from hyperthermia in cars across the country.
"Tragically, we've not seen the numbers go down."
Jan Null is a researcher from San Francisco State University who tracks heatstroke deaths involving children in cars.
He says in most cases, the parents or caregivers forgot the child was in the car. But in about 30% of the cases, toddlers gain access to a vehicle on their own.
"Sometimes they can climb into the trunk. They are overcome by the incredible heat that can build up inside a vehicle."
Null says parents should always keep their car doors locked and car keys out of the reach of kids.