GALE-FORCE winds of up to 100km/h are expected to hit Sydney and the south and mid north coast of NSW.
The Bureau of Meteorology has issued a severe weather warning and predicts damaging winds across Sydney, the Hunter, Illawong, the south coast and the mid north coast on Friday.
The State Emergency Service is urging residents to secure outdoor furniture and bring unsecured items indoors.
Cars should also be parked in the garage.
Electricity providers warned people to stay clear of fallen power lines that might be brought down by wind gusts.
Power lines could remain live despite not being attached to the electricity network.
It is extremely dangerous to touch or approach fallen power lines, Ausgrid said in a statement.
