The State Emergency Service is advising people to remain alert in the severe weather conditions.
Residents are encouraged to check that loose outdoor items are safely secured, move vehicles under cover and to stay indoors.
If you are travelling do not drive through floodwater.
SES state agency commander David Baker said Victorians should be aware of changing weather conditions.
"It is forecast that slow moving storms will bring heavy rainfall with the potential for flash flooding across the state," he said. "Just this afternoon She Oaks recorded 54mm in 50 minutes.
"Flash floods can happen quickly, without warning and it is important to never enter or drive through flood waters, as it can take just 15 cm of water to float a car.
"Stay aware of your surroundings and if you're travelling or are in unfamiliar places, make sure you are aware of the local risk."
The Department of Transport is urging motorists to take care on the roads as severe weather moves across the state.
High winds have seen speeds on the West Gate Freeway reduced to 60km/h while heavy rain and large hailstones are expected in Central, Mallee, South West, North Central, Wimmera and parts of East Gippsland, Northern Country, North East and West and South Gippsland forecast districts.
"Bad weather should prompt drivers to slow down and use extreme care," a statement from the department reads.
"Conditions can change quickly. Be vigilant at all times and ensure there are no distractions that will take your focus off the road.
"Make sure loads are secure, particularly on elevated roadways."
Drivers are encouraged to take extra safety precautions such as leaving more distance between cars, using headlights, ensuring loads are secure and pulling over if rain becomes too heavy for windscreen wipers.
A lightning strike in Kangaroo Flat has caused rail equipment to fail.
The incident is expected to delay services in both directions on the Bendigo line by up to 20 minutes.
A severe thunderstorm warning has been issued for most of Victoria with the potential for heavy rainfall and hailstones.
The warning says a low pressure trough has combined with a very humid and unstable airstream.
Severe thunderstorms are likely to produce heavy rainfall that may lead to flash flooding and large hailstones in the warning area over the next several hours.
Locations which may be affected include Mildura, Horsham, Warrnambool, Bendigo, Maryborough, Ballarat, Geelong, Melbourne and Traralgon.
Thousands of people are now without power after rain and lightning arrived in the central Victorian region.
According to the Powercor website, 2955 customers in the Bendigo area have lost power.
Suburbs affected include White Hills, North Bendigo, East Bendigo, Long Gully, Epsom, Ascot, Huntly, Jackass Flat, Strathdale and Strathfieldsaye.
About 740 customers are listed as without power between Newbridge, Maldon, Castlemaine, Harcourt and Elphinstone.
Power is expected to be restored by 5.30pm.
THOUSANDS of central Victorians are without power after outages hit the state.
Castlemaine is among the hardest hit, with electricity down for at least 1300 users.
Kangaroo Flat, Golden Square, Taradale, Elphinstone, Metcalfe and Lockwood have also been affected.
CENTRAL Victorians have been warned to stay indoors if heavy thunderstorms hit the area on Friday afternoon.
The Bureau of Meteorology has forecast severe thunderstorms that may lead to flash flooding over the next few hours, in areas including Bendigo and Maryborough.
The storms are likely as a humid and unstable airstream moves across the state, with a slow-moving low pressure trough in the west.
The State Emergency Service advises people to stay indoors and away from windows.
If outdoors people should move to a safe place indoors, and stay away from trees, drains, gutters, creeks and waterways.
If driving conditions are dangerous people should pull over away from trees, drains, low-lying area and floodwater.
The City of Greater Bendigo has cancelled its planned music in the park event at Canterbury Park due to the forecast.
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