Hail, flash flooding and heavy rain are expected in Melbourne on Friday afternoon, just as commuters head home for the weekend.

The Bureau of Meteorology warned severe thunderstorms would bring dangerous weather across swathes of the city for several hours from 2pm on Friday.

"These thunderstorms … are forecast to affect [suburban] Laverton, Scoresby and Werribee by 3.10pm and Melton, St Kilda and Williamstown by 3.40pm," the bureau said.

"Heavy rainfall may lead to flash flooding and large hailstones are likely."

Flash floods, hail, rain: Nightmare for Friday commuters_1
The storm warning for Melbourne. Image: Bureau of Meteorology

The weather bureau said Sheoaks, 100 kilometres west of Melbourne, had already recorded 54 millimetres of rain in 50 minutes on Friday.

The threat to Melbourne was accompanied by a more general severe thunderstorm warning for other parts of Victoria, including the Mallee, west and South Gippsland, Wimmera, and areas in the state's south-west, north central and parts of East Gippsland, the northern country and north-east districts.

There was also a warning for NSW residents, with slow-moving storms expected to bring heavy rain and hail to inland and southern areas.

Friday's weather warnings came as ex-tropical cyclone Uesi was due to pass close to Sydney later on Friday and early Saturday, bringing dangerous surf conditions.

A hazardous surf warning is in place for much of the NSW coast on Friday and for the Hunter, Sydney, Illawarra, Batemans Bay and Eden on Saturday.

Other parts NSW can expect more wet weather at the weekend, following last week's deluge, particularly the bushfire-ravaged South Coast, the Southern Tablelands and western Sydney.

Thousands of residents in Sydney and the Central Coasts are still without power.

Ausgrid said 13,000 customers were still without power on Friday and aimed to have services fully restored by Sunday night.

The rain has brought much-needed relief for firefighters, with the NSW Rural Fire Service on Thursday confirming there were no uncontained fires for the first time this season.

It has also given a boost to Sydney's parched dams. Warragamba Dam was at more than 76 per cent capacity on Friday, up from 43 per cent a week ago.

-with AAP