Sydney has disappeared under grey clouds and heavy rain for the second morning in a row, with the wet weather likely to continue for the rest of the week.
A heavy burst of showers hit the city at 7.30am, while Campbelltown received 18mm in an hour from 6am and Box Hill was drenched with 70mm since 9am yesterday, Weatherzone meteorologist Rob Sharpe said.
No let up yet for soggy Sydney
The state of our climate in 2016
Video shows mass coral bleaching of Great Barrier Reef
Shark attacks: Australia's most dangerous beaches
Coastal erosion: a sign of things to come?
Victoria receives 'significant' bushfire warning
Snake breeding season slithers into Sydney
New dinosaur discovered in Queensland
No let up yet for soggy Sydney
Heavy rainfall in Sydney's west this morning has been over the amount needed to cause flash flooding, says meteorologist Rob Sharpe.
A heavy burst of rain hit the CBD just before 9am sending commuters dashing for shelter.
The Bureau of Meteorology issued a severe weather warning for heavy rain in Sydney, south coast, Illawarra, Hunter and mid north coast areas.
"Sydney is expecting some very heavy rainfall today with the chance of flash flooding," Mr Sharpe said.
"The eastern suburbs of Sydney are going to be the hardest hit, so both the north-east and the south-east suburbs."
Mr Sharpe said the rain would start to clear late tomorrow.
"The clearing trend will begin on Thursday with longer breaks between showers.
"But the showers [will] quite possibly continue through the weekend, although they'll be lighter."
A spokesman for the Transport Management Centre said there were very few problems on Sydney's roads and transport networks before 8am.
School holidays meant that there was less traffic on the roads and more space between vehicles, he said.
On the northern beaches Oxford Falls Road was closed in both directions between Wakehurst Parkway and Morgan Road due to flooding.
NSW State Emergency Service spokesman Phil Campbell said there were 45 calls for help across the state last night, mostly in the coastal areas of Sydney.
"Most of the damage we're getting is just leaky roofs because of the heavy rain," he said.
Fallen trees and branches have also damaged parked cars in Canterbury and Blacktown.
He urged people to stay away from flash flooding, storm water drains and creeks.
Mr Sharpe said Sydney was still on track to break its April rainfall average of 126mm.
The Transport Management Centre provided this list of flooded roads at 10.50am:
* Wakehurst Parkway, North Narrabeen - closed.
* Oxford Falls Road, Oxford Falls - closed between Wakehurst Parkway and Morgan Road.
* Syd Einfeld Drive, Bondi Junction - one eastbound lane closed near Old South Head Road.
* Newbridge Road, Chipping Norton - one lane closed in each direction at Governor Macquarie Drive.
* F3 approaching Hawkesbury River Bridge - water affecting southbound traffic.
* Bexley Road, Campsie - traffic affected in both directions at Canterbury Road.
* St Marys Road, Windsor Downs - closed at Sirus Close (low level causeway).
* Luxford Road, Mount Druitt - two eastbound lanes closed at Carlisle Avenue.
Additionally, a burst water main in North Parramatta has closed one southbound and one northbound lane of Church Street at Pennant Hills Road.
Motorists are advised to exercise caution, drive to the conditions and not attempt to drive through flooded areas.
Updates are available here.
- with Steve Jacobs
Weatherzone.com.au is owned by Fairfax Media, publisher of this website.