Heavy rains lash Sydney, prompting chaos

Flights were cancelled, railway lines closed and motorists stranded on flooded roads as a month's worth of rain fell on Sydney early Wednesday, leaving emergency services battling to respond.

Severe thunderstorms and heavy rainfall lashed Australia's largest city, with the local Bureau of Meteorology reporting more than 73 millimetres of rain fell in less than an hour in some places.

The city usually sees an average of 84 millimetres for the entire month of November.

Electricity providers reported at least 3,500 people were left without power, and emergency services said they had received at least six flood rescue requests even before most workers had finished their morning coffee and begun the daily commute.

They urged residents to use caution and not drive vehicles into flooded roads: a "major cause of death during floods is by people entering floodwater. Find an alternate route and avoid unnecessary travel."

At the city's main international airport, multiple flights were cancelled or delayed and aircraft were left stranded on the tarmac as ground crews took shelter from the downpour and electrical storms.

"Due to adverse weather conditions today, we expect that International and Domestic terminals will experience some flight delays and cancellations," said the airport authority.

Rainfall was forecast to slow, but continue throughout the day.

Australia is no stranger to extreme weather, experiencing flash floods, sandstorms and even extreme drought in areas that are now being inundated.