Gale-force winds, 'cricket ball sized hail' and flash flooding devastate Sydney

The Australian Bureau of Meteorology issued a rare tornado warning on Wednesday

Storm clouds gather over Sydney Harbour in Sydney (PETER PARKS/AFP/Getty Images)

Extreme weather in Australia, causing gale-force winds and 'cricket ball sized' hail, has devastated parts of the country resulting in flash flooding, airport closures and power outages.

The Australian Bureau of Meteorology (BOM) issued a warning on Wednesday as a rare tornado swept up the coast through Sydney.

Social media was swamped with pictures of huge, dark clouds looming over the harbour city, as the storm plunged a 25 degrees summers day into darkness.

Strong winds brought down trees, power lines, tore off roofs in some areas and forced a number of international and domestic flights to be diverted to other cities.

Wind gusts as high as 132mph were recorded in the neighbourhood of Kurnell, near Sydney’s airport, said the weather bureau.

A spokesman for Sydney International Airport said the airport had not closed but a handful of flights had been diverted.

Grounded flights caused delays for commuters traveling out of Sydney causing passengers stuck in heavy traffic to abandon their cars, The Sydney Morning Herald reports.

Multiple thunderstorms dropped hail the size of cricket balls, damaging cars and smashing windows.

Flash flooding in Sydney city and the eastern suburbs damaged buildings and trapped people in their cars.

The State Emergency Service said they had responded to around 600 call-outs by 6:30pm on Wednesday in parts of southern Sydney, as well as Bondi, Bellevue Hill, Maroubra and Port Botany.

Shoppers were evacuated from Bondi Junction Westfield and a woman was taken to St Vincent's hospital with head and elbow injuries after a section of the shopping centre's roof collapsed.

"There is a lot of roof damage, trees down, power lines down. And in Sydney's east it has been mostly incidents of flash flooding," said Sue Pritchard, a SES spokesperson told The Sydney Morning Herald.

Some 6,000 homes were reportedly without power south of the city, according to media reports.

Australia is currently experiencing an El-Nino weather pattern, a phenomenon associated with extreme droughts, storms and floods, which is expected to become one of the strongest on record, according to the UN weather agency.

Margareta Wahlstrom, the special representative of the UN secretary-general for disaster risk reduction, said Australia should prepare itself for more extreme weather, particularly drought over the summer months, ABC Australia reports.

Ms Wahlstrom said: "Australia I can see will be getting drier in all likelihood.”

Additional reporting by Reuters