Around 250 State Emergency Service (SES) volunteers are working late into the night to repair the damage from wild storms in the Sydney area.

The SES received more than 360 calls for assistance in the Sydney metropolitan area, with 190 of the calls coming from the Penrith area.

Thirty millimetres of rain fell in 15 minutes across the Penrith area just after 2:00pm (AEDT), causing the roofs of the Penrith courthouse and a nearby shopping centre to partially collapse.

The State Emergency Service says a motorist had to be rescued from his car after it became stranded in localised flash flooding.

The fire brigade says it is dealing with a number of call-outs in the Penrith area.

It says those needing help should call 132 500 and only call triple-0 if the situation is life-threatening.

Phil Campbell from the SES says the storm threat has eased.

"Those storms don't appear to have caused significant damage in other locations," he said.

The storms left trains to Newcastle and the Central Coast running more than a hour behind schedule.

Meanwhile, a golfer has died after he and two others were struck by lightning in a storm at Hawks Nest, north of Newcastle.

One man was flown to hospital with burns.

For the latest thunderstorm warnings visit the Bureau of Meteorology website.