Paramedics were called to eight reports of children locked in vehicles on Wednesday across the state.

Two were in regional areas and six were in the metropolitan area.

A pre-school aged girl was assessed by paramedics after being left with a primary school aged child in a hot car at Narre Warren South at about 4.30pm.

The girl wasn't taken to hospital.

Ambulance Victoria is urging people not to leave children and pets in cars.

There has been an increase in triple Zero (000) calls in the past few days.

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Earlier: Warrnambool has one of the state's highest incident rates of children being locked in cars, new data reveals.

Information released by RACV's emergency roadside assistance shows nine children were rescued from locked cars in Warrnambool this year.

It's the fifth highest incident rate in Victoria behind Malvern East (10 incidents), Hoppers Crossing (13) and Frankston and Pakenham (14).

The statistics were released as part of RACV's Check Keys - Check Kids campaign, designed to prevent parents and carers from accidentally locking children in hot cars.

RACV spokesman Bryce Prosser said vehicle cabin temperatures could more than double in the hotter months.

"Car interiors can reach more than 70 degrees in just minutes when the outside temperature is only 30 degrees," he said.

"Especially around this time of year, it's easy to become distracted and forget where our car keys are. A momentary lapse in concentration combined with sophisticated vehicle locking technology and soaring summer temperatures is a recipe for disaster."

Last month a young child became locked inside a vehicle near the Warrnambool Base Hospital after wind blew the door of a Honda CRV shut.

Emergency services were called and fire brigade officers unlocked the vehicle and freed the child.

Warrnambool Fire Brigade officer in charge Greg Kinross said hyper vigilance meant there were more reports of children being stuck in cars.

"When people see kids in cars they will contact emergency services immediately and police, fire and ambulance automatically respond," he said.

"Sometimes we get a report and by the time we get there the people have already driven off. There is also occasions where parents have accidentally locked their keys in the car.

"It's often no one's fault but people do need to be vigilant about leaving their keys with their kids because they can just press the button that locks the door."

RACV emergency roadside assistance patrolman Steven Kendall, who has rescued hundreds of kids from cars over his 30-year career, said it was important parents remained calm if they ended up accidentally locking a child in a car.

"Knowing the dangers vehicle lock-ins pose to young children, RACV prioritises these call-outs as urgent and we allocate the job to the closest RACV crew," Mr Kendall said.

"Once on scene, we attempt to unlock the door with our expertise and tools, but depending on the temperature outside and the make of the vehicle, we may end up breaking a window to get the child out."

In Victoria it is an offence for a person responsible for a child to leave the child unattended for any longer than is reasonable, without making appropriate arrangements for the child's supervision and care.

That includes leaving a child unattended in a car.

The penalties for leaving a child unattended in a car in Victoria include a fine of up to about $4000 and/or a maximum of six months' imprisonment.

To avoid locking your children in the car, you should:

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