Multiple severe thunderstorms rolled across parts of Sydney on Australia's east coast on Thursday, raining down massive hailstones.

Craig Ryan from Australia's Bureau of Meteorology said a combination of humidity and warm temperatures were "providing the ingredients" for extreme weather conditions.

According to the State Emergency Service, the worst-hit suburbs were Liverpool and Berowra, with "almost every second home" in Berowra needing assistance.

The Insurance Council of Australia (ICA) has declared the storm an "insurance catastrophe" with damages estimated to be worth millions of dollars.

Reports of "extensive damage" to cars and homes had been received from Sydney’s west to Bondi Beach, some 7 kilometers (4 miles) east of the Sydney central business district, an ICA spokesman said.

Both cars and homes were impacted by flash flooding. Social media lit up with pictures of smashed windshields and damaged roofs.

Sydney Airport said the bad weather had caused delays of up to 90 minutes for the domestic and up to three hours for the international flights.

Read more: What is a 'bomb cyclone?'

According to the Bureau of Meteorology, Sydney residents should expect some showers on Friday and a heatwave over Christmas, but no more thunderstorms are forecast.

Australia is no stranger to extreme weather, experiencing flash floods, sandstorms and extreme drought and wildfires in some areas.

Queensland is still recovering from bushfires last month, while Cyclone Nora brought heavy rain and flooding to the far north of the state in March.

Read more:  In the eye of the firestorm: Surviving Australia's most extreme bushfire