A total of 800 children have been locked in a vehicle since January 2016, according to new figures from AA.
The numbers paint a picture of the serious threat to children whose lives were put at risk.
During a typical summer day, the temperature inside a car can reach up to 60 degC - even with windows down - and it's enough to cause brain damage or kill a child or pet.
In December, the AA was called to 90 emergency jobs involving children or pets locked inside vehicles.
AA Road Service national manager John Healy says people should be mindful, especially over the summer period, because being forgetful can result in serious consequences.
"Holiday brain definitely takes its toll at this time of year, but the real danger is when there are children and pets locked inside the car," says Mr Healy.
Mr Healy says the biggest cause of AA's emergency jobs is people accidentally locking their keys inside their car.
"We had a mum who ended up in a situation like this just before Christmas," he says.
"She dropped her keys into her handbag on the passenger seat and left it there so she could get her baby out first. She shut the door behind her and the vehicle locked with her baby, keys and phone all inside the car.
"Thankfully she managed to borrow a phone and get in touch with us and we had her baby out of the car within minutes."
He says parents and caregivers need to make sure they always have their keys on them when they're in and around their vehicles, especially if kids and pets are inside.
The numbers say it all:
- Lock out and lost key callouts (December 1 - January 22): 5107
- Lock out and lost key callouts in 2016: 34,672
- Children and pets locked in cars (December 1 - January 22): 152
- Nearly 100 lockout jobs every day since December 1 - a total of more than 5100.