Police confirm the latest fatality was a 49-year-old man who died in Caboolture, north of Brisbane.

On Saturday morning police confirmed a 75-year-old man died at Burpengary overnight after his car was swept away by floodwaters near Burpengary Creek at about 8.30pm.

Swift water rescue crews managed to save a 68-year-old woman who survived by clinging to a tree.

"Everywhere from the Nambour region through to central region got between 200 and 300mm, since 9am yesterday," Bureau of Meteorology forecaster Julian De Morton said.

"That was really due to a large amount of convergence - moist air converging along a trough."

Southeast Queensland's beaches were pounded by monster surf, with a 13 metre swell recorded at Tweed Heads at one point.

A severe weather warning remained current for dangerous surf on the Gold and Sunshine Coasts on Saturday.

"The weather today is going to be pretty good, but the surf conditions are still dangerous," Mr De Morton said.

"We've still got around four metre waves - and quite powerful waves - around the Gold Coast."

The Queensland Fire and Emergency Service (QFES) performed more than 30 swift water rescues and on Saturday morning there had been over 1800 requests for help.

QFES spokesman Brian Cox urged motorists to be cautious.

"The storm has passed but there's still danger on the roads," he told ABC radio.

"There's a hell of a lot of pot holes that have been revealed."

Nearly 2500 homes and businesses were still without power on Saturday morning, with the majority in the Gold Coast region.

Premier Annastacia Palaszczuk confirmed the deaths of a man, woman and child at a media conference at the Kedron emergency services headquarters on Friday night. 

"On behalf of all Queenslanders we express our deepest sympathies... this is a tragedy and it's not an easy thing to talk about," she said.

"Tonight we are deeply saddened by this tragic loss of life."

Assistant Police Commissioner Alistair Dawson said a full investigation would take place into the deaths, but confirmed floodwaters had been involved.

Police were notified around 5.30pm of the incident on Dances Road at Caboolture.

A man in his 70s, a woman in her 30s and an 8-year-old boy were pronounced dead at the scene after their car was swept away in floodwaters.

Ms Palaszczuk said Caboolture had been particularly swamped by the low pressure system that caused widespread flash flooding and commuter chaos throughout the day.

"To put it in perspective, in Caboolture from 9 o'clock this morning there has been more than 333 millimetres of rainfall, in the afternoon in just a three hour period there was 277 millimetres," she said.

"Having just spoken to the Bureau of Meteorology, for them, this is off the scale."

The Premier said the system was moving south, with heavy rain expected on the Gold Coast and hinterland areas before clearing away after midnight.

Ms Palaszczuk said Gold Coast beaches would be closed on Saturday, and again called on people to stay at home and off the roads where possible.

"The SES has recorded some 1400 incidents over the course of the day, and these include issues such as people being stranded in cars, people being on the rooftop of their cars, and there have been 19 swift water rescues in Brisbane alone," Ms Palaszczuk said.

"This has been an extreme weather event."

A girl was reportedly struck by lightning, close to a dozen motorists were rescued from floodwaters and afternoon commutes were thrown into chaos as rain lashed south-east Queensland on Friday.

The Caboolture area was the hardest hit as slow-moving, highly concentrated storm cells dumped more than 300 millimetres of rain in a few hours.

The roads were a hazardous place to be all afternoon but those heading home to the Sunshine Coast suffered particularly as major roadways went under water.

The Bruce Highway was cut both ways at Burpengary just as peak hour approached, while water and debris at Elimbah and Griffin also caused major delays.

Road closures due to flooding on Gympie Road, Aspley, and Steve Irwin Way at Beerburrum didn't help matters.

At the same time, the south-east corner's public transport network was thrown into chaos with trains suspended on the Caboolture, Sunshine Coast, Airport, Doomben and Shorncliffe lines.

Kangaroo Bus Lines suspended all school buses and several bus stops went under water.

Emergency services were frustrated as motorists ignored constant pleas to stay away from flood waters.

Swift water rescue crews pulled seven people from floodwaters in one incident north of Brisbane and were rushing to close to about half a dozen other rescues about 4.15pm.

Air traffic was also impacted, with most Virgin Australia afternoon flights in and out of the Gold Coast cancelled and sizeable delays at Brisbane Airport as storm activity forced people off the tarmac.

The east coast low that dumped between 50 and 150 millimetres of rain on most of the south east was heading south towards the New South Wales border by Friday evening.

But not before the widespread rain led to event cancellations across the region.

The three-day Urban Country Music Festival at Caboolture had to be completely cancelled, along with the Jan Powers' Farmers Markets at both Manly and the Brisbane Powerhouse.

Friday night's Anzac Test at Suncorp Stadium was rescheduled to Sunday afternoon.

While the severe weather seemed to catch many residents on the hop despite days of warning, BOM senior forecaster Michael Knepp said the system performed pretty much as expected.

The highest rainfall recorded was 327 millimetres at Caboolture, the majority of which fell after 1.30pm, while Maroochydore copped a wind gust of 81km/h and Cape Moreton recorded 109km/h.

"It was just a general rainfall, light to moderate and then it really picked up in the afternoon as forecast," Mr Knepp said.

"This is what we expected, so no surprising elements.

"As part of our warnings we did say 200, 300 millimetres is definitely possible and widespread 50 to 150 and that's what we've experienced really."

The Bureau of Meteorology update on Friday evening still contained a severe weather warning, but the outlook did appear to be improving.

The low system is moving south along the coast, supported by a strong upper trough moving across southern Queensland. Both will move away from the south coast on Saturday.

However, heavy rain and flash flooding was expected over the Gold Coast and hinterland Friday evening, with average falls of 50 to 150mm and isolated falls of 100 to 200mm. 

Dam operator Seqwater says water releases from Wivenhoe and North Pine dams are likely on Friday night or Saturday morning.

Water has been released from Somerset Dam into Wivenhoe, and 11 dams in the region are overflowing.

The weather bureau has issued flood warnings for the Tweed River and rivers along the coast from Maryborough into northern NSW, extending as far south as Nelson Bay.

Saturday is likely to start with heavy rain and possible storms, but improve to be partly cloudy. 

- with AAP

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