Victoria's SES has received more than 1,500 calls for help with more heavy rain expected in the central, east and north-east of the state overnight as authorities prepare for possible evacuations in some parts.

The state is enduring what the weather bureau says is an "unprecedented" deluge that could bring three months' of rain in three days, with another 150 millimetres forecast to fall in some areas.

Melbourne has avoided the worst of the thunderstorms over the past 24 hours, but there are now numerous road closures around the capital, particularly in the eastern and south-eastern suburbs.

Elsewhere in the state, emergency workers are paying particular attention to the north-east ranges, where significant flooding is expected and warnings have been issued for a number of rivers, including the Ovens and King rivers, the Broken River, Seven and Castles rivers, and the Kiewa River.

People have been advised to prepare to evacuate low-lying areas of Myrtleford along the Ovens River, and a relief centre has been opened at the Myrtleford Senior Citizens club.

People in Harris Lane and Wallace Drive on the Buckland River were also issued a prepare-to-evacuate notice. Authorities said properties could be inundated or isolated and the bridge could become impassable.

Some homes have already flooded at Euroa, local Nationals MP Steph Ryan said.

Sandbags have been in high demand in Euroa. ( ABC News: Stephanie Anderson )

People were evacuated from a local caravan park and residents turned out at the local SES depot to fill and distribute sandbags.

"The town is very, very wet at the moment," Ms Ryan said.

"I checked in with the SES first thing this morning. They were aware of a number of houses that have been inundated and people who have been evacuated.

Sorry, this video has expired The Victorian Premier says parts of the state will see entire summer's rainfall in one day.

Melbourne to see another dump of rain overnight

Bureau of Meteorology senior forecaster Scott Williams said more heavy rain would hit the north-east overnight as storms move through to southern New South Wales.

Emergency contacts: For emergency assistance call SES: 132 500

For emergency assistance call SES: 132 500 For emergency incidents and warnings: http://emergency.vic.gov.au/respond

For emergency incidents and warnings: http://emergency.vic.gov.au/respond For weather warnings: http://www.bom.gov.au/vic/warnings

For weather warnings: http://www.bom.gov.au/vic/warnings For life-threatening emergencies call 000

He said Melbourne would get more rain from about 6:00pm onwards, with the heaviest rainfall expected around the Plenty River and Diamond Creek catchments.

Minor flood warnings have been issued for the Yarra River and Dandenong Creek.

Melbourne could see totals of 20-40mm overnight so the potential for flooding remains, the Bureau said.

"Melbourne's going to be a very wet place on Saturday night, and that rain will ease on Sunday morning," Mr Williams said.

"We always watch out with these events for what we sometimes call the sting in the tail before the low finally moves away."

The Sevens and Castle creeks are in flood around Euroa. ( ABC News: Stephanie Anderson )

Mr Williams warned Victorians to continue to pay attention to the warnings.

"It takes time for water to get down into rivers and to flow to the lower parts of those rivers where population centres are," he said.

"Already there are numerous moderate flood warnings around Victoria for rivers, this will continue to go on for quite some time after the rain stops."

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SES state agency commander David Tucek said more than 1,500 requests for assistance had been received since the start of the rain event, including from parts of Melbourne and locations such as Echuca and Euroa in the state's north-east.

"Generally it's been related to flooding more so than anything else, so sometimes it's been water coming up close to people's properties and there's been a lot of water coming in through gutters, windows and the like," he said.

"Some of the rainfall's lessened off around Melbourne parts, however we've certainly seen the rain continue in a very heavy fashion up around north-eastern parts."

The SES responded to two calls for help from people whose cars got caught in floodwaters at Balmattum and Cathkin near Euroa early on Saturday.

Mr Tucek said a couple in their 70s were caught in their car in floodwaters near Seymour.

"It was a local farmer in a tractor that came to their aid and got them out of the water," he said.

Sorry, this video has expired Roads were closed around Myrtleford as waters rose.

The state's heaviest falls have been recorded at the Strathbogie Ranges, where Mt Wombat recorded 190mm of rain.

Echuca received a record daily rainfall of 123mm, and daily rain records were broken in Euroa and Eildon, with 146mm and 148.6mm in 24 hours.

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Mr Williams said the focus had shifted eastwards to the Oven and upper Murray catchments.

He said high areas of those catchments could see up to 100mm between Saturday afternoon and Sunday morning.

"It's not out of the question that quite a few event totals could exceed, or reach, around 250mm in the north-east," he said.

Parts of Gippsland could also see isolated falls of more than 150 millimetres, the bureau said.

Parts of Melbourne experienced flash flooding on Friday, when 40mm of rain fell in places.

Sporting and social events have been cancelled across the state, including the Taste of Melbourne food festival, and several carols by candlelight concerts.

The last two days of the Great Victorian Bike Ride, which was due to head to Glengarry on Saturday, have been cancelled.

Transport is being organised from Maffra to get people home.

Emergency services defend warnings

Residents in some low-lying areas of Euroa have been told to prepare to evacuate. ( ABC News: Stephanie Anderson )

Emergency Management Commissioner Craig Lapsley justified the severity of the warnings saying 250mm of rain was forecast in some areas, and 150mm had already fallen with more to come.

"Our job is to make sure that forecasts are able to be communicated to the Victorian community and we've done that," he said.

"The hardest [thing] is understanding timing and intensity of location [of the rainfall]," he said.

Melbourne was spared the worst of the rain but more is on the way and a weather warning remains in place. ( ABC News: Danielle Bonica )

"That's one of the challenges. So we've done … the best we can to warn the whole of the Victorian community, because there was rain across Victoria, and … we've seen rain move across Victoria.

"In some cases exactly what the forecast said, in others it hasn't been exactly. However I think the figures that are there today show that we've had significant rain."

For the first time, an emergency SMS was sent to 7.4 million Victorians in areas most at risk.

Kerang residents have awoken to find many of its streets flooded after last night's downpour. ( Twitter: Scott Bourne )

It said: "SMS from VicSES. Flooding is expected across Victoria this weekend. Heaviest rain on Saturday. Check on family & friends. Stay informed."

Mr Lapsley said there had been concerns that some people had received the warning more than once.

He explained that the messages sometimes were repeated when they went out on multiple towers or if a person was on the move.

"That is the system to ensure there are no gaps," he said.