PHOTOS: Wild weather and heavy rain have caused chaos across Sydney

Brook Mitchell/Getty ImagesThunderstorms build at sunrise in Bronte this morning.

A low pressure system sweeping across Sydney has caused widespread flooding, and road and rail closures across the city as a month’s worth of rainfall came down in just 90 minutes.

The inclement weather is set to continue throughout the day, with the SES responding to nearly 300 calls, including 12 rescues from cars entering floodwaters.

Police are urging motorists to take extra care on the roads. Widespread closures and delays

Assistant Commissioner Michael Corboy, Traffic & Highway Patrol Commander, said the conditions are some of the worst he’s ever seen.

“Once again we are asking all road users to reconsider the need to be on the roads throughout what will be a severe rain event today,” he said.

“Drivers need to consider reducing their speed to make sure they have enough braking distance for themselves and for the vehicle in front, and to drive to the conditions.

“We can’t stress enough that motorists should never attempt to drive through floodwaters or cross flooded causeways.”

In the early hours of this morning, thunderstorms brought the heaviest rain, with 84.6 millimetres falling at Observatory Hill between 5.20am and 7am, beating the November average of 83.8mm.

Mosman saw 61mm of rain fall in just 30 minutes, while 70mm fell at Olympic Park Olympic Park over the same period from 6am.

By 9am, Mosman had 111mm of rain.

The north shore, hills district, inner west and CBD, including West Pymble, Concord, Marrickville and Glebe have been hit by flash flooding as the heavens opened around 5.30am.

Water was seen pouring from the walls of Woolworths at Sydney Town Hall, while the T1 and T3 rail lines were temporarily closed due to flooding, but are now operating again, however Lewisham station is closed, along with the light rail service.

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Parramatta River ferries have also been shut down.

Sydney Airport is once again down to one runway with delays and cancellations expected. The terminal is packed with hopeful passengers, with long queues, and multiple flights cancelled.

Around 5000 homes in northern Sydney lost power.

Dozens of roads are closed and Marg Prendergast Coordinator General for Transport for NSW said she had one of the scariest drives to work in her career, and urged motorists to avoid driving if possible.

The rain is expected to continue throughout Wednesday, stretching from Newcastle in the north to Wollongong in the south, with up to 200mm predicted to fall, accompanied by strong winds gusting up to 90km/h as the lower-pressure system moves east and out to sea.

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