Half a million lightning strikes hit Victoria's skyline as wild storms lash the state

Thousands of people across Melbourne and Geelong remain without power after a severe storm swept across the state overnight.

Half a million lightning strikes were recorded, with one sparking a blaze at a home in Taylors Lakes.

Napoleon and Simone Trombetta's Taylors Lakes home of 35 years was hit by one of 50,000 bolts of lightning that made contact with the ground.

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The couple were in bed about 1am when their dog Frankie began to be distressed by the storm.

Moments later, the pair heard a "massive bang" before seeing a red glow from their lounge room.

"The smoke detector went off and looking from our bedroom there was a red glow, we jumped out of bed and got out there as fast as we could," Simone told 9News.

"I grabbed Frankie and my handbag and that was it."

The house has been extensively damaged from the fire, with the couple believing the fire started by a lightning strike.

It was a wild night of storms across Melbourne and Victoria more broadly, with Geelong particularly hard-hit.

The sporadic storms first hit the Mornington Peninsula, before jumping across to the Surf Coast and settling in over the city just before 11pm.

More than 900 calls for help were made over downed trees and building damage, with 200 calls to the SES in just one hour at one point.

More than 500 of those calls were in the greater Geelong area, where 80km/h winds uprooted trees and ripped roofs and brickwork off homes.

Belmont resident Dee Dove and her family were inside their Belmont home when a tree crushed their front fence.

"It was like a cyclone, I mean I've never ever experienced anything like it in all my time - it's crazy," Dove said.

"We were so lucky. There's other people around here who've lost their roofs.

"It actually makes me emotional."

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At its peak, the wild conditions left 45,000 customers without power, with a few thousand still waiting to regain electricity as of this afternoon.

The dynamic thunderstorm activity saw about 30mm of rain fall in Geelong and Lara in just 30 minutes.

Hail stones with a diameter of two to four cm also pelted the Otways and Geelong.

About 70mm fell in the Macedon Ranges overnight, but the weather system failed to quench the state's bushfire-stricken Grampians region, where just 10mm fell.

The storms followed a day of high heat, with a top of 39 degrees in Melbourne.

That high will be duplicated again today, followed by 34 degrees tomorrow.

A heatwave warning has been issued for the state.

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ADF to build temporary bridge to give access to flood-ravaged town

More thunderstorms are also expected to move across the south-west of the state this evening, with the Bureau of Meteorology predicting a risk of dry lightning.

"We're not out of the woods yet and we've had a taste of it yesterday," SES Victoria deputy chief officer David Baker said.

"We're still looking down the barrel of storm activity this afternoon and tomorrow.

"Storms can appear anywhere, at any time, but the best time to prepare is before the storm arrives."

The combination is a worry for firefighters, who are still battling two out-of-control blazes in the state's west.

Temperatures will drop to a top of 23 degrees for Melbourne on Wednesday before rising again later in the week.

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