The fast-moving storm cell lashed the western suburbs on Sunday afternoon, dumping heavy rain on Penrith and Richmond before heading north-east.

"The thunderstorms were short and sharp," said NSW SES duty officer Neil Wiblin. "Damaging winds were contained in the thunderstorm and it was really severe and very fast moving," Mr Wiblin added.

The SES responded to 175 calls for assistance across the city, with most of the calls related to fallen trees and powerlines.

Weatherzone meteorologist Craig McIntosh said the worst of the storm was expected clear the Sydney area by 8pm.

"There will be lingering storms ... short sharp bursts of rain, and the heaviest showers will be at the leading edge of the storm."

Emergency crews worked to restore power to about 900 homes in Panania in Sydney's south-west, after the storm caused a blackout.

Power's out to about 900 homes in parts of Panania. Emergency crews are working to get it back safely. https://t.co/MxbaFPxBlK??? Ausgrid (@Ausgrid) April 9, 2017

The downpour caused headaches for train services on Sunday evening, with delays affecting trains on the T3 Bankstown Line and T2 Inner West and South Line.

Trains were also halted on Sydney's City Circle due to urgent equipment repairs after the storm caused damage.

Sydney Trains said services resumed about 7.50pm after the repairs were carried out, however passengers were still warned to allow extra travel time.

#InnerWestLine 19:16 Central to Homebush service delayed up to 15mins due to urgent track equipment repairs caused by severe weather??? T2 Sydney Trains (@T2SydneyTrains) April 9, 2017

Mr McIntosh said the rain would linger overnight before dissipating.

Sydney is set for its coldest morning of the year on Monday, with temperatures in the CBD expected to drop to 12 degrees overnight.

Temperatures will remain cool throughout Monday, with a top of about 20 degrees expected for the CBD.

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