Large parts of Sydney have been battered by severe, damaging thunderstorms for the second day in a row.
The super storm cell lashed NSW late on Saturday, punishing parts of the state with winds of more than 100km/h that brought down trees and powerlines.
Driving rainfall and hail has smashed Sydney's west and northwest, with 36mm of rain falling at Strathfield in just 15 minutes and 42mm received at Goulburn.
Widespread flash flooding swept across the city, with the State Emergency Service receiving more than 500 calls for help on Saturday afternoon.
Rescue crews have launched dozens of flood rescues.
Among those saved was a 50-year-old man who clung to a tree at Edmondson Park, in Sydney's southwest, for more than two hours after his car was swamped by floodwaters.
An entire unit block at Lidcombe in western Sydney was evacuated after the building's roof blew off, while a house's roof in the Blue Mountains collapsed in ferocious weather.
Power has been cut to more than 50,000 homes and businesses across Sydney, with the Sutherland area by far the hardest hit.
"Emergency crews are being hampered in patrolling these areas to make safe and commence the restoration process by ongoing lightning and heavy rain," Endeavour Energy said in a statement.
Traffic lights hit by the power outage caused some chaos for drivers, while some shoppers in the Sutherland Shire browsed supermarket aisles by torchlight.
SES spokeswoman Sue Pritchard again warned people to steer well clear of floodwaters.
"Don't drive through them, don't walk through them, don't let your kids play near them," Ms Pritchard told AAP.
"We've had so much rain lately that anything that hits the ground is going to run off, and there are so many spots where it's just too dangerous.
"If you're driving and come across floodwaters, stop, turn around and find another way."
Heavy rains are expected to stick around well into Saturday night, before conditions ease considerably on a mostly sunny Sunday.
