Paramedics attended hundreds of cases of children left in hot cars over December despite repeated warnings about the dangers of leaving children unattended on summer days.
Ambulance Victoria figures show paramedics were called to 225 cases of children left in cars last month.
On one day that hit 37 degrees there were 13 call outs. And the problem appears to be getting worse with the latest figures far exceeding the 161 call outs a year ago in December 2014.
The latest campaign to persuade people of the dangers is called No Exceptions, No Excuses. The state government public service announcement will be launched just as the temperature is forecast to exceed 40 degrees on Wednesday.
Parents or carers who leave their children unattended in a car can face fines up to $3700 and six months' jail.
The campaign will highlight how quickly cars can heat up even when parents or carers run quick errands or make short visits to shops.
Acting Premier James Merlino said the community was being urged to take the safety message seriously.
"We continue to face hot conditions this summer – there are no excuses for leaving kids in cars," he said.
The awareness campaign will include radio and online advertising, billboards and posts on social media.
Families and Children Minister Jenny Mikakos said children should not be left alone "even for just a moment".
Ambulance Victoria director of emergency management Paul Holman said December 3 and 17 were the busiest days, with 13 calls for children left in cars on each day.
"Some of these cases were accidents, while others appear to be deliberate," he said.
Mr Holman said Ambulance Victoria tests had shown on a 29 degree day the temperature inside a car could reach 60 degrees in 20 minutes.
"Tragically we've seen three children die in recent years after being left in a car on a hot day," he said.
Bureau of Meteorology senior forecaster Rod Dixon said the temperature was expected to reach 41 degrees in Melbourne on Wednesday. However, a cool change forecast for Wednesday evening is expected to bring in cooler conditions for the end of the week.
Mr Dixon said the rest of summer could still be hot although the long-term outlook included a lower chance of hot conditions after January.
"For the rest of January and the early part of February we'll still see some pretty hot days," he said.
Separate figures released last year showed up to five children were being left alone in hot cars every day. The Ambulance Victoria statistics revealed the suburbs of Pakenham, Narre Warren, Preston and Epping had the greatest numbers of children locked in cars.