Experts claim Sydney storms ‘abnormal’ for December

For an incredible seventh straight day, perfect storm conditions have threatened Sydney.

Ominous cloud formations formed above the city, producing torrential rain and lightning.

The city's west and southwest bore the brunt of it, with motorists suffering treacherous driving conditions.

In Wiley Park, a man was trapped in his car by a fallen tree branch. The Birrong IGA was also affected by water damage from a leaking roof.

The wild weather has all being caused by a persistent low-pressure trough and moist and unstable air.

Experts said the weather is more typical of January and February.

"This spell of week-long storms is fairly unusual for this time of year," Weatherzone's Anthony Duke said.

Residents are still assessing the damage caused by last night's storm.

A lightning strike zapped through a power point in one Balgowlah unit, sparking a fire that destroyed the kitchen and everything in it.

The couple who rented the unit were luckily not home.

Sydneysiders are expected to face more storms and heavy rain tomorrow.