A woman has died after her car was struck by a falling tree branch near the NSW Southern Highlands.

The woman was travelling along the Illawarra Highway at Macquarie Pass near Clover Hill Road when the severe weather dislodged the branch about 4pm today.

A man believed to be travelling in the front seat of the car suffered minor injuries, while two people in the back seat were not physically injured.

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The notorious road is expected to be closed for several hours while emergency services work at the scene.

The tragedy is one of hundreds of jobs emergency services have been called to over the past few days as wild weather lashes communities near the NSW coast.

As heavy rain poured down over the past 24 hours, State Emergency Service (SES) volunteers helped several people trapped in their cars as flash flooding hit Albion Park, Picton and Marulan.

NSW SES Superintendent Matt Kirby warned residents to heed the warnings from authorities.

"This weather can produce heavy rainfall and strong winds, so we remind people not to drive through floodwaters and be wary of where you park your vehicles as tree branches can fall at any time," Kirby said.

"Download the Hazards Near Me app to stay up to date with any warnings that have been issued."

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Heavy rain has already drenched parts of the state over the last two days in the worst storm of the summer.

In Moruya, almost 200 millimetres of rain fell in the 48 hours to 9am today.

A slow-moving pressure system was predicted to bring up to 120 millimetres of rain in some parts of the NSW coast over the following 24 hours.

Heavy rain and damaging winds were likely to continue in Sydney, the Blue Mountains, the Illawarra and Shoalhaven over the next 48 hours.

Severe thunderstorms are also likely across the Central Coast and Mid North Coast regions, which could cause isolated rainfall of up to 120 millimetres in the next 24 hours, along with strong winds and hail.

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