Residents in parts of Sydney have been hit by a severe thunderstorm producing damaging winds and hailstones, with warnings of more wet weather on the way.
The weather bureau said the situation was "rapidly evolving" as three storm cells merged into one and moved towards the state's southeast.
It was forecast to affect Hornsby, Parramatta, Sutherland, Sydney Airport, Sydney Olympic Park, the Sydney Harbour Bridge, Mona Vale and waters off Bondi Beach.
A severe storm warning was also issued for people in Penrith, Parramatta, Wollongong, Nowra and Campbelltown.
Senior meteorologist Sarah Scully said people should expect more severe thunderstorms on Wednesday afternoon.
"Large hail, damaging wind gusts and heavy rainfall that may lead to flash flooding are all still possible" she said.
"This trough and low pressure system (will) start to skirt away tomorrow into the Tasman Sea, dragging away the worst of the weather with it."
The NSW State Emergency Service said people should move their cars away from trees or under cover and secure loose items.
Wet weather has battered parts of NSW for multiple days, leaving communities on alert to the possibility of flooding.
SES volunteers were kept busy through Christmas and Boxing Day, responding to 473 calls for help and conducting six flood rescues.
More than 80 jobs were recorded in the state's northeast on Boxing Day, after four-centimetre hail caused havoc near Maitland in the Hunter Valley, shattering windows and damaging vehicles, skylights and roof tiles.
The suburb of Rutherford was hit particularly hard, with more than 50 people calling for help in less than an hour after copping the brunt of the hail.
