A severe thunderstorm warning has been issued for Sydney and a large part of New South Wales, with the metropolitan area expected to be hit by 2-centimetre hailstones and damaging winds.
The Bureau of Meteorology said Newcastle, Gosford, Sydney, Wollongong, Bowral, Orange, Mudgee, Bathurst and Katoomba could all be affected.
The storm, which has already lashed Penrith in the west, is predicted to reach the Sydney CBD about 3:00pm.
BoM duty forecaster Miranda Langton said Sydneysiders should take care.
"We have reports of 2-centimetre hail, so that could be damaging to things like cars," she said.
"There is a chance it could last all night."
The State Emergency Service has advised people to move their cars under cover or away from trees, secure or put away loose items and stay at least eight metres away from fallen powerlines.
Regions that could be affected include the Hunter, Metropolitan, Illawarra, Central Tablelands and parts of the Mid North Coast, Southern Tablelands and North West Slopes and Plains.ABC