Swathes of Victoria have been put on notice to expect rainfall totals as high as 150mm to 200mm when thunderstorms sweep across the state on Sunday and Monday.
Victorian State Emergency Service personnel have responded to more than 110 requests for help with at least 53 flood-related rescues since 6am Sunday.
Some areas in the state's north have recorded more than 45mm of rain since 9am.
South Australian and southern NSW areas are also in the firing line of the major weather event.
Rain and severe storms are building across parts of eastern Australia, with heavy falls a risk over the coming days. Warnings are current. For the latest forecasts and warnings visit — Bureau of Meteorology, Australia (@BOM_au) https://t.co/4W35o8iFmh or the BOM Weather app. pic.twitter.com/IgKtRVPtvOJanuary 7, 2024
The SA State Emergency Service warned of the potential for heavy rain, strong winds, hail and lightning as thunderstorms swept across the state on Saturday night before moving over eastern border districts from Sunday morning.
The SES has responded to over 90 calls for help on Sunday after fast-flowing floodwaters blocked roads in the Flinders Ranges.
Storms knocked out Coober Pedy Hospital's power supply but the SES said the hospital was functioning normally on backup power.
The Bureau of Meteorology also issued a warning for severe thunderstorms and flash floods across parts of southern NSW from Saturday evening to Tuesday.
VIC SES Commissioner Rick Nugent said flash flooding was highly likely along many of the state's already sodden rivers and creeks following recent rain.
Residents of flood-prone areas, as well as campers and holiday-makers in caravan parks, were urged to prepare and be on the lookout for emergency flood warnings.
"Falling tree branches and flash floods are the highest risk," Mr Nugent told reporters.
"Please don't drive through floodwaters - you're driving a car, not a boat."
The storms were expected to develop in Victoria's west on Sunday morning, before moving through central, north central and eastern parts of the state during the day and into Monday.
Storms are expected to develop in Victoria's west before moving through central and eastern regions. (Mal Fairclough/AAP PHOTOS)
Some areas in Victoria's Mallee and Wimmera districts could record up to 60mm of rain in less than an hour, meteorologist Michael Efron said.
"The amount of moisture across the state at the moment is incredible," Mr Efron said.
"It's what you would normally see in somewhere like Queensland."
SES crews established sandbag collection points at high-risk locations such as Bendigo, Castlemaine, Campbells Creek, Heathcote and Wedderburn from Sunday.
The flood threat comes as residents affected by recent severe storms in southeast Queensland were offered more federal assistance.
About 99 per cent of the 130,000 homes and businesses impacted by storm-induced power outages have now been reconnected.
One-off disaster recovery payments of $1000 per eligible adult and $400 per child will be made available from Monday to residents in the Gold Coast, Logan and Scenic Rim region.
A disaster recovery allowance will also be offered to affected employees and sole traders who have lost income, providing 13 weeks of income support.
Emergency Management Minister Murray Watt said the federal government was working closely with Queensland authorities for recovery efforts following the storms.
"It won't be fixed overnight, there is very significant damages in both ends of the state," he told reporters on Sunday.
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