SES volunteer dead after collapsing during Sydney storm clean-up

A State Emergency Service volunteer has collapsed and died while on duty as Sydney deals with the aftermath of a deadly thunderstorm. Follow the latest updates in the Tele live blog. 

Flash flooding is predicted to impact Sydney once again this afternoon

A State Emergency Service volunteer has died while helping clean-up NSW in the aftermath of a severe thunderstorm.

In a statement, the NSW SES said the volunteer member collapsed while on duty and police are preparing a report for the Coroner.

"NSW SES Commissioner Mark Smethurst and the NSW SES family send our heartfelt condolences to the family and fellow Unit members." the statement said.

It's understood the man, aged in his 40s, was working with a crew in Shellharbour in the Illawarra.

Council workers clear a drain on Railway Terrace in Lewisham. Picture: Dean Lewins

A man has died in a two-car crash in rain-drenched Thornleigh.

It follows the death of a teenage boy during a head on car crash at Thornleigh this morning.

The 14-year-old was killed when the Toyota Corolla he was travelling in collided with a Landrover before hitting a parked car.

His older teenage brother, 17 who was driving was uninjured and taken to Royal North Shore Hospital for assessment.

It was a dangerous day across the city with the Bureau of Meteorology recording 105.6mm of rain at Observatory Hill from 3am to 9am.

The northern Sydney suburb of Chatswood recorded 105mm to 9am, while the Illawarra region was soaked with 139mm of rain during the same period.

The most heavily affected area was West Pennant Hills in Sydney’s north-west, which was hammered with a staggering 72mm in the hour between 5.30am and 6.30am.

Meanwhile, Mosman on Sydney’s lower North Shore copped 61mm of rain in just half an hour between 6am and 6.30am.

A Bureau of Meteorology spokeswoman still have a severe thunderstorm warning in place over the Sydney Metro area, which poses a risk of more storms, heavy rain and possible hail.

“We’re still monitoring the weather over the Sydney Metro and Hunter regions,” she said.

“It does look like the low system is forming further north than anticipated...it does look like its becoming less of a risk.”

Since the storm began in the early hours of Wednesday morning, Sydney has been drenched with 124.8mm of rain.

See the Tele gallery of today's weather chaos here.