Vicious storms, hail the size of 50c pieces hit Sydney with more wet weather to come this weekend

A severe thunderstorm hit much of Sydney this afternoon, with multiple lightning strikes hitting the Harbour Bridge and the turbulent weather causing chaos during the evening peak hour.

The Bureau of Meteorology issued a storm warning just after 1.30pm on Friday, while Sydney airport was forced to delay various outgoing flights.

It was also reported that a 36-year-old man was taken to hospital after being hit by lightning on a construction site in Rouse Hill in Sydney's north west this afternoon.

Commuters suffered through a frustrating journey home with numerous bus and train services cancelled due to severe storms and traffic grinding to a stand-still on many of the city's roads.

And the weekend isn't looking too good for Sydneysiders with the storms expected to continue overnight and into Saturday.

The Transport Management Centre advised commuters on Friday afternoon to delay their trip or allow "plenty of additional travel time".

Meanwhile, beachgoers at Bondi and Coogee were sent fleeing as ominous clouds rolled Sydney's Northern Beaches including Palm Beach and Avalon shortly after 4pm.

Shortly beforehand Bellambi reported gusts up to 90 kilometres per hour. Hail has been reported at Penrith in the city's west.

Multiple fast-moving storms have hit the Penrith region, southwestern Sydney and near Wollongong, a spokeswoman told AAP.

Penrith was 36 degree at 1pm, but the temperature plunged 10 degrees in half an hour.

Fallen lines should be reported to “either Ausgrid on 131 388, or Endeavour Energy on 131 003 or Essential Energy on 132 080, as shown on your power bill”, the BOM warning said.

The NSW State Emergency Service received 200 calls in just a few hours in the afternoon and several hundred more throughout the evening.

In Lilyfield, gale force winds and repetitive lightning strikes saw one house lose a roof and a Toyota Yaris trapped under a large gumtree.

The SES advises people to tie down any loose items in backyards or on balconies.

People have also been advised to avoid driving cars if possible.

Sydneysiders have been warned to keep their vehicles away from trees and to remain at least eight metres away from fallen power lines.