Flights were cancelled and trains suspended as intense rain and flash flooding wreaked havoc in Sydney on Wednesday morning.
The NSW State Emergency Service received almost 260 calls for help by 7am, including 11 flood rescues.
"It's turning into being a wild day," SES regional controller Greg Murphy told Seven Network.
According to Weatherzone, Observatory Hill received its entire November monthly average in "less than two hours".
"Between 5:20am and 7am, the city collected 84.6mm and the November average is 83.8mm," it tweeted.
Drivers have been told to stay off the roads as public transport across the city has been similarly affected.
Social media users have been sharing images and video of the wild weather under the hashtag #SydneyStorm.
A number of flights at Sydney Airport have been delayed or cancelled, with the airport reduced to just one runway.
Cancelled flights at Sydney Airport. Source: Ricardo Goncalves
More than 6000 properties are without power, including hundreds of businesses in the CBD.
NSW Police said drivers, riders, cyclists and pedestrians needed to take extra care, increase their visibility with headlights and bright clothing and increase braking distances.
"We're asking all road users to perhaps reconsider the need to be on the road through what will be a severe rain event," Chief Inspector Phillip Brooks told reporters on Tuesday.
SES Assistant Commissioner Scott Hanckel even advised people try to arrange to work from home if possible.
He was hopeful the SES would have thousands of volunteers available to call on across the South Coast, Hunter and Sydney metro areas, should people need help with fallen trees or flooding.
