A quick call to her husband led to Mrs Barker realising her daughter was still in her car seat, inside her husband's pick-up truck.
According to police, Mrs Barker rushed home and pulled her one-year-old out of the ute just before 6pm to perform CPR before paramedics arrived.
Katera was rushed to Vanderbilt Children's Hospital but was pronounced dead on arrival.
Mr Barker arrived home late that night and police said the couple are being fully cooperative with their investigations.
No charges have been filed yet in regards to Katera's death.
Every Australian summer, police issue dire warnings to parents about forgetting about their children in the back seat.
In January, NRMA's Peter Khoury said the danger of leaving kids in cars cannot be overstated — adding that temperatures can double inside a car within five minutes.
"In Victoria, temperatures have been reaching 40C," he said. "That means the temperature inside the vehicle can reach double what it is outside — then you're starting to reach low cooking temperatures and that's no place for a child or pet.
"Sometimes, it's a case of someone running in to get a coffee and even that is extremely dangerous.
"It just takes minutes. There's no airflow in the vehicle. Children and pets become dehydrated and distressed within minutes and it doesn't take long for organ failure to kick in.
"Unfortunately, we have seen cases around the world and in Australia where children have died and it's due to organ failure and dehydration.
"Cars are not meant to be used as babysitters. Your car could also get stolen, someone could break in — so you shouldn't leave your child in the car at any time, regardless of the weather."
On average, 37 children die from heat-related deaths after being trapped inside vehicles worldwide, according to the safety organisation Kids and Cars.
