Sydney swamped as entire streets go under

Flood evacuation orders have been issued for low-lying areas north and south of Sydney as the NSW coast is battered by its most torrential downpour since 1998.

Utility companies were on Sunday rushing to turn the lights back on for the more than 100,000 customers left without power.

On Sunday night, the NSW State Emergency Service ordered an evacuation of a large area of Sydney's southwest, including the Bankstown Aerodrome and the suburbs of East Hills, Holsworthy, Milperra, Moorebank, Picnic Point, Pleasure Point and Sandy Point.

"Evacuate immediately if safe to do so," the SES said.

The SES has also ordered evacuations at Narrabeen Lagoon in Sydney's north and the low-lying areas of Narrabeen and the Hawkesbury River at North Richmond Lowlands.

Residents around Narrabeen Lagoon were ordered to evacuate by 10.30pm.

"NSW SES is directing people within Narrabeen Lagoon to evacuate the high danger area using Pittwater Road or Ocean Street," NSW SES said.

"Once floodwater (reaches) 2.4m Pittwater Road will be cut. If you remain in the area after 10.30pm you will be trapped without power, water and other essential services and it may be too dangerous to rescue you. This flood will be higher than the 2016 flood of the Narrabeen Lagoon."



If residents are unable to stay with family or friends outside the flood area, an evacuation centre has been established at Mona Vale Memorial Hall on Park Street, and at the Cromer Community Centre on Fisher Road North.

Residents of Moorebank, Chipping Norton and Milperra were ordered to evacuate by 7pm. The affected area is all properties on Arthur Street, Rickard Road, Davy Robinson Drive and Newbridge Road between Milperra Bridge and Riverside Road.

"Once floodwater reaches 3.3m the streets will become inundated and evacuation route cut," NSW SES said. An evacuation centre has been established at Dunc Gray Velodrome on Carysfield Road, Bass Hill.

"Take pets, essential items, warm clothes, medicines, insurance documents and valuables with you," NSW SES said.

"Leave as early as possible to avoid restricted road access. Take drinking water and food due to expected travel time. Share this information with family, friends and neighbours and help others where possible."

It comes as hundreds of millimetres of rain have drenched the coast, sparking warnings of high winds, "life-threatening" flooding and landslips. Scores of roads have been closed and the train system has been thrown into chaos.

Flooding along the Hawkesbury River could disrupt gas and water deliveries to the northwest Sydney towns of Richmond and Windsor, the SES said.

Emergency services have been swamped with calls since the deluge set in on Friday, while the extreme weather has caused transport chaos across Sydney.

"This wet and windy weather is really wreaking havoc on our roads today, with paramedics responding to five car accidents every hour since Friday night," NSW Ambulance spokesman Giles Buchanan said on Sunday afternoon.

"We've responded to multiple trees that had fallen onto cars, trees into houses and units, and people trapped in cars in floodwaters."