Police have confirmed that a man has died after a car was washed away in floodwaters at South Burnett, northwest of Brisbane early Friday morning.

“We are working to formally identify this person,” Police Inspector Scott Stahlhut told reporters.

“We have a number of officers on scene, our forensics and dive people are here.”

There have been multiple reports of other cars in floodwater as a powerful offshore weather system moves south along Australia’s east coast.

South Burnett Regional Council issued an emergency alert after flash flooding hit the area.

Eleven people had to flee their vehicles at a Nanango caravan park early on Friday morning, the ABC reported.

Swiftwater rescue crews are at the town’s Twin Gums Caravan Park where more than a dozen caravans have been impacted by floodwaters.

The council warned roads and bridges may be impacted and urged residents to stay off the roads.

A surfer surveys the swell at Snapper Rocks. (Image: Cathy Border/ABC News)

The local school in Nanango will be closed on Friday, Premier Annastacia Palaszczuk said.

“Please follow advice from emergency services and if it’s flooded, forget it,” Ms Palaszczuk tweeted.

Emergency crews responded to two separate incidents when drivers found themselves in trouble on roads about three hours north west of Brisbane.

A woman was assessed at the scene and didn’t need to be taken to hospital after an incident on the Bunya Highway near Kingaroy early on Friday morning.

Two people in their 50s also avoided injury when a car entered floodwater on Kumbia Road in Brooklands.

Rainfall totals of more than 100mm have been reported in the Sunshine Coast hinterland, with the town of Maleny among the hardest hit.

Damaging winds averaging around 50 kilometres per hour are possible in exposed parts of the coast, and peak gusts may reach 110km/h on Fraser Island, also known as K’gari.

There is also a minor flood warning in place for the Stanley River at Woodford, about an hour north of Brisbane.

The low-pressure weather system is expected to move south on Friday and Saturday, and beaches have been closed on the Gold Coast because of the dangerous conditions.

Wild surf is forecast for the NSW north coast from Friday, with wave heights of more than five metres possible.

Dangerous beach conditions could affect the popular seaside towns of Tweed Heads, Byron Bay, Ballina and Yamba.

The warning comes as thousands of music fans make their way to Byron Bay for the Splendour in the Grass music festival, where campers faced long queues to enter.

“The weather and staff shortages were all worse than expected,” a message on the festival’s Facebook page said late on Thursday.

“We are doing the best we can – the show will go on rain, hail or shine.”

ABC News journalist Tobias Loftus, who is at the festival, said the conditions were miserable.

“It’s just so wet here, and there’s mud everywhere,” Loftus said.

“I’m so thankful I brought my gumboots. I’ve seen so many people around the place that don’t have gumboots on. Hopefully they can find some inside once the main festival gates open.

“It’s not Splendour in the Grass this year, it’s Splendour in the Mud.”