It is believed the damage bill could run into tens of millions of dollars after cars were hammered, windows in homes and business were smashed and roofing was torn away.

Some Melbourne car dealerships estimate their bills would could reach up to $2 million, with hundreds of cars battered by the hailstorm causing up to $5000 of damage per vehicle.

Up to 600 cars at the Ferntree Gully KIA & Hyundai dealership on the Burwood Highway were battered by the hailstorm.

On Wednesday managers were scrambling for clarification from their insurance companies.

"They've got bad damage," dealership manager Martin Luby said.

"We are waiting on the insurance companies to give us direction."

Independent used car dealership Just Used Cars, also on the Burwood Highway, said all of his 25 cars in stock were damaged. Some had already been sold.

"I might have to give them a discount," owner Craig Prato said.

"The insurance companies are hopeless I won't use them, I'll just try and sell these."

Petrina Lloyd from a nearby mega-dealership that sells Holdens, Nissans, Suzukis, Volkswagens and used cars said 80 per cent of their stock - or "hundreds of cars" - had been damaged.

"It includes damage to bonnets and roofs and smashed windscreens."

Ferntree Gully Honda reported 100 damaged cars, while service centre Garry and Warren Smith Mazda reported five cars damaged.

Meanwhile thousands of people remain without electricity after the massive storm-front ripped through the state, pelting suburbs with giant hailstones and leaving a trail of flood and other damage.

???The east and south-east of Melbourne were worst hit, with golf ball-sized hailstones raining down as thunder cracked.

At the peak on Tuesday evening, there were 100,000 homes without power, with about 11,000 still without electricity on Wednesday afternoon.

The area hit hardest by power outages was the north and north-east of the state, including Bendigo, Shepparton, Mildura, Kilmore and Benalla. Cranbourne was also hit.

Emergency services had expected power to be restored by early afternoon, however repairs were taking longer than expected.

The SES is reminding people that refrigerated or frozen food that is no longer cold to the touch must be eaten within four hours or thrown out.

Emergency services were doing flyovers on Wednesday morning to make sure there were no bushfires started by lightning.

Warrigal Road - from Canterbury Road to Riversdale Road - remains closed due to a "significant landslide" that happened about 10pm on Tuesday night. VicRoads was unable to say when the road would be re-opened and advised drivers to avoid the area.

Bureau of Meteorology forecaster Peter Blake said the worst of the weather had passed Melbourne and that the storm had moved quickly into parts of north and eastern Victoria by late Tuesday night.

He said some of the highest rainfalls were recorded at Mount Useful (40 millimetres), Officer (35mm), Hampton Park (34mm), Doncaster (32mm) and Kardinia (32mm).

Melbourne was hit with 20 millimetres of rain in just 15 minutes which caused flash flooding on Tuesday evening in areas including Richmond, Brunswick, Brighton, Moonee Ponds and the CBD.

In Melbourne's CBD, 16.4 millimetres of rain fell within the 15-minute period from just after 8pm, while Mount Buller was the worst hit with 22.2 millimetres of rain in the 15-minute period.

The State Emergency Service responded to 2000 calls in relation to the storm across Victoria, with 582 of those still active on Wednesday afternoon.

The SES's Manningham unit (Bullen, Doncaster, Donvale, Templestowe, Warrandyte) responded to most call-outs, followed by the Mildura unit. Those two areas were the worst hit according to the SES, with most calls related to fallen trees, fallen powerlines and damaged buildings.

There were so many requests for assistance that Country Fire Authority volunteers were called in as back-up.

Early on Wednesday morning there were numerous calls for assistance coming out of Wallan and Wangaratta. Residents reported building damage, flooding and fallen trees.

The left lane inbound on Dynon Road near Kensington Road, West Melbourne, will remain closed during Wednesday morning peak hour due to flooding over the road.

VicRoads said the water wasn't clearing due to the height of the Maribyrnong River and that motorists should expect delays through the area.

There are power outages for a small amount of residents surrounding the Warrigal Road landslide while some 250 residents were without power near St Georges Road in Northcote.

A spokeswoman for Melbourne Airport said all runways were operating as normal after only one was open during the storm. The spokeswoman advised travellers to check with airlines for any delays.

Lights went out on late-night Christmas shoppers at Highpoint Shopping Centre in Melbourne's west as rain poured in from the ceiling.

But despite the roof leaks and a power outage during the storm, the centre is open for business as usual, a spokesperson said.

The Telstra Store is open but with some cleaning still occurring while Mazzuccelli's will open for normal trading later today and Diana Ferrari tomorrow.

Nick Addison was inside his house in Templestowe watching the thunderstorm with his four-year-old daughter when they heard a deafening sound outside.

"We were just looking up at the lightning across the sky then all of a sudden we heard this pretty loud banging and kept going so we went out the front to take a look," he said.

"There were huge hailstones everywhere.... I picked a few of them up and they were easily golf ball size."

Mr Addison said his car was protected under a double garage, but friends and family living nearby in Templestowe weren't so lucky.

"I know my friend's car has copped a fair bit of damage and hailstones just pelted through my parents' pergola," he said.

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