More rain expected today after sudden Sydney storm

More rain is expected after a sudden storm rolled across Sydney yesterday afternoon, knocking out power to tens of thousands of homes.

One of more than 10,000 lightning strikes in the city on Wednesday afternoon hit a man's house, sending firefighters and ambulance crews rushing to the scene. 

Power was lost in a string of suburbs in the city's north, such as Hornsby and Asquith, but had been restored by 9pm, according to Ausgrid.

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A handful of domestic and international flights were delayed at Sydney Airport, and three cancelled, although it was unclear if they were all weather related.

Horsley Park in the city's west recorded 26mm of rain, and more is expected today.

The Bureau of Meteorology has forecast showers for Sydney during the day.

But Weatherzone reported storm activity would largely clear, with the city in for a cooler top of 19 degrees, compared to 27.5 degrees yesterday.

Lightning sets house on fire

In the eastern suburbs, emergency services were called to a home in Maroubra at 5.30pm after it was struck by lightning.

Resident Simon Hodge was at home when he heard a bang followed by a knock on the door.

"The biggest bang I've ever heard in my life, just scared the bejesus out of me," he said.

"Next thing I know, someone was banging on the door saying lightning struck the building and there's smoke coming out of it."

Firefighters and ambulance crews attended the scene.

Storms with the potential for large hail and damaging winds swept across parts of New South Wales and Queensland.

Residents in the two states woke up to relatively dry and clear weather before the system brought showers and storm clouds to the skies by mid-afternoon.

"They're bringing hail and they're bringing strong winds throughout much of south-eastern Queensland and the northeast of New South Wales," Bureau of Meteorology senior meteorologist Angus Hines said.

The system moved through Campbelltown in Sydney's south-west and circled in the inner city late this afternoon.

Heavy hail hit multiple areas in NSW including Murwillumbah on the North Coast, Parkes in the Central West and the Southern Highlands south-west of Sydney.

A severe thunderstorm warning in place for the north-eastern corner of NSW near the Northern Rivers area was cancelled in the afternoon, along with another warning in south-east Queensland.

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Widespread storms in the Sunshine Coast hinterland extended down to the area north of Brisbane.