A huge storm cloud cast a dark shadow over Sydney as it dumped 30mm of rain on the city in just half an hour.
The dramatic dark clouds that rolled in brought thunderstorms that caused chaos for rush hour commuters as roads and rail lines were flooded.
Buildings in central business district shook as the storm hit, local media reported.
The state's emergency service advised people to keep clear of fallen power lines, creeks and storm drains and urged people to avoid riding their bikes or driving through flood water.
Flights were diverted to other major airports until the thunderstorm - which brought winds of up to nearly 40mph (60kph) - passed.
Social media was awash with images of the spectacular storm as Sydney residents described the clouds as rolling in like a "wave".
The day had been warm and sunny for the most part until the clouds rolled in.
Although forecasters have now downgraded the risk, they say there is storm potential for the next few days.
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