Temperatures in Melbourne topped 31.7 degrees just after 4pm on Sunday, and a sweltering 37.3 at Charlton in the state's north-west, when a band of forecast storms rolled through the western suburbs.

The hot and humid weather with forecast storms had authorities fearing Sunday afternoon could see a repeat of the thunderstorm asthma emergency.

Thunderstorm activity was reported between Laverton and Geelong on Sunday afternoon, though minimal rainfall was recorded – and there was no repeat of the massive fallout from the November 21 event that claimed eight lives and sent thousands to hospital.

Paramedics responded to several dozen calls for breathing difficulties on Sunday afternoon, an Ambulance Victoria spokesman said, though it was unclear how many were weather-related.

The National Asthma Council Australia had earlier issued a warning for people who experience wheezing and sneezing to "take extra care" ahead of the storms.

The Bureau of Meteorology is now forecasting a cold front to roll into Victoria from the west late on Sunday evening, bringing a slight chance of thunderstorms.

Senior forecaster Dean Stewart said there was a slightly higher risk of thunderstorms when the cool change was expected to roll through Melbourne.

The wind change has been forecast to arrive in Melbourne between 5am and 6am on Monday with the increased risk of thunderstorms to last until around 8am, he said.

"There's a chance of storms with that change going through in the morning," he said.

A total of 4mm of possible rainfall has been forecast for Monday.

Ambulance Victoria had rostered an additional 15 crews for Sunday.

State health commander Paul Holman said extra paramedics would be on the road and extra staff would be available to take calls.

But no additional crews have been rostered for Monday.

Tim Cartwright, Victoria's acting police chief commissioner in 2015, is leading the review into Ambulance Victoria's handling of the deadly thunderstorm asthma event.

Ambulance Victoria's chief executive Tony Walker welcomed the inquiry.

"We know there were a number of families who lost loved ones and it is essential we review every aspect of our response so we can learn lessons from events such as this," he said.

Victoria's Chief Health Officer, Professor Charles Guest, warned people with a history of asthma, hay fever or allergies were at particular risk in the conditions predicted for Sunday night.

"Thunderstorms, combined with pollen in the air, can cause an increase in asthma symptoms, hay fever and breathing difficulties," Professor Guest said.

"When there is a thunderstorm or severe weather warning in spring or summer, staying indoors with windows closed and in air conditioned areas will reduce exposure to pollen."

Dr Burdon said thunderstorm asthma occurs when a storm strikes on a hot and windy day when there are high levels of pollen in the air.

When the storm front hits the pollen grains absorb the moisture and burst into tiny particles, where they can then get inhaled deep inside the lungs and trigger a serious asthma attack.

Dr Burdon warned people should follow their asthma action plan and always carry a puffer.

Pharmacies have reported a rush on asthma-related products following the thunderstorm asthma event.

A total fire ban was also activated for Victoria's Mallee region on Sunday and the CFA advised people living in areas at risk to activate their bushfire plan.