A severe thunderstorm warning has been issued for residents in the Hunter and mid north coast regions.
The Bureau of Meteorology is warning of storms that could produce large hailstones, heavy rainfall that may lead to flash flooding and damaging winds in the Gosford, Scone, Cessnock and Maitland areas of NSW.
Keen amateur photographers took the opportunity to snap some incredible images of the advancing storm cells as they passed over Sydney.
A previous severe storm warning for the Sydney, Illawarra, South Coast, Central Tablelands, Southern Tablelands and Snowy Mountains districts has been cancelled.
The State Emergency Services has advised residents to unplug computers and appliances, avoid using the phone during the storm, stay indoors away from windows, and keep children and pets indoors as well, for emergency help in floods and storms, ring the SES (NSW and ACT) on 132500.