Asthma thunderstorm forecaster needed

Ambulance Victoria wants a system to predict future thunderstorm asthma events so resources aren't wasted every time a storm appears on the horizon.

The organisation received "several dozen" calls from people with breathing problems on Sunday afternoon as thunderstorms rolled across the state.

But of the 60 respiratory cases recorded, only four were active treatment for asthma.

"All the others ... had nothing to do with what we would term thunderstorm asthma," Ambulance Victoria state health commander Paul Holman told 3AW on Monday.

Victorians have been on high alert about the potential for thunderstorm asthma attacks after eight people died after a storm event two weeks ago.

Extra ambulance crews were rostered on Sunday as authorities warned asthmatics of the potential increased risk.

Mr Holman said that was partly to reassure the community.

"I don't want to be doing this every time we see a thunderstorm on the horizon because we're just wasting resources," he said.

"Aggressive" work was now underway to develop a scientific thunderstorm asthma forecasting system.

"If it can be predicted, then we can take some action in terms of health warnings and resourcing."

Victorian temperatures peaked at 37.3C in Charlton on Sunday with 31.7C recorded in Melbourne.

Thunderstorms hit the city's west, areas around Port Phillip Bay, the inland north and central highlands.

"It's looking more settled for the next couple of days," Bureau of Meteorology senior forecaster Chris Godfred told AAP on Monday.

"But we do have another relatively strong cold front that's going to move across Victoria on Thursday morning that will bring widespread showers and the risk of storms."

Thunderstorm asthma is caused when dust and pollen is blown in or ahead of a storm.

Moisture causes pollen grains to burst into tiny fragments that can penetrate deep into the airways.