Since January 1, RACV patrols have responded to calls to rescue four children and one animal every day, on average, from hot cars.
Young children and dogs made up the majority of cases, with RACV’s Melinda Congiu saying a hot car can become life-threatening to those trapped inside.
“Locking anyone in a car – especially a vulnerable small child - is extremely dangerous and unacceptable,” Ms Congiu said.
“Many parents give their keys to their child to play with but this is a dangerous practice as children can accidentally lock the car."
The RACV says research has shown it can take just 90 seconds for the temperature inside a locked car to climb from 19 to 30 degrees, with temperatures topping 60 degrees or more on a hot day.
Some parts of Australia experienced record-high temperatures during the 2012/13 summer, with more hot weather predicted for this summer.
“People may think it is okay to leave children in a car for a short time as they run an errand but by doing so they are creating a life-threatening situation for that child,” Ms Congiu said.
“There is never a safe time to leave children in the car. Young children are more sensitive to heat than older children or adults as their body temperature can rise three to five times faster.”
Despite the RACV prioritising call-outs for vehicle lock-ins, the motoring group has stressed that the few minutes it can take for a patrol to reach the scene can make an enormous difference when temperatures are extreme.