In short:
Heavy rain is expected between the Sunshine Coast and northern NSW.
Two people have been rescued from their cars in floodwaters and numerous roads are closed.
What's next?
Conditions are expected to ease tomorrow and into the weekend.
Brisbane's Ekka parade has been postponed as heavy rainfall causes havoc for the show's organisers.
The weather bureau is warning of heavy rainfall and storms for south-east Queensland and northern New South Wales as a front passes over the region.
The Bureau of Meteorology says up to 100 millimetres could fall in the Sunshine Coast hinterland on Wednesday and parts of the Gold Coast are forecast to receive up to 80mm.
Crowd numbers at the Ekka show are down, with the main arena waterlogged and the grand parade postponed to Saturday.
The wet weather has caused wastewater to be released into the Brisbane River at Morningside, with Urban Utilities advising people to temporarily avoid contact with the river between Vic Lucas Park at Bulimba and Colmslie Beach Reserve at Murarrie.
In NSW the State Emergency Service is warning North Coast residents to prepare for heavy rain and flash flooding.
Two people were rescued after being caught in floodwaters last night and SES crews responded to dozens of calls for help.
There is a hazardous surf warning and a strong wind warning from the Capricornia Coast to the NSW border.
All Gold Coast beaches are closed.
Rainfall records tumble
Coastal communities between Mackay and Hervey Bay have copped a drenching over the past two days the weather system is now moving south.
Rockhampton recorded its highest-ever August total when 85mm of rain fell overnight.
SES crews in Central Queensland responded to 38 calls for help in response to flash flooding and several roads remain closed.
The SES received 12 calls for assistance on the Sunshine Coast.
Emerald has recorded 66mm of rain this month, which is the highest August total since 1999.
Sunshine Coast Airport has recorded 61mm since 9am on Tuesday, making it the wettest August day since 2007.
On the Gold Coast, Springbrook has recorded 72mm, but some areas could receive another 100mm before midnight.
Two rescued from cars
A woman in her 60s was taken to hospital after her car was caught in floodwaters at Ban Ban Springs, south-west of Bundaberg, last night.
On the Sunshine Coast a man in his 20s was rescued after his car was trapped in floodwaters in Palmwoods at about 10pm on Tuesday.
He was not injured.
NSW SES Superintendent Scott McLennan said people should avoid travel where possible.
"Get your provisions, check your gutters, check your systems, make sure you know what your emergency plan is," he said.
Minor flood warnings remain in place for the Burnett, Boyne, Kolan, Burrum and Cherwell Rivers in Queensland, and the Wilsons, Orara and Lachlan rivers in NSW.
'Never knock it back'
Emerald farmer Neek Morawitz said he was celebrating the unseasonal weather.
"It's pretty unusual to have this sort of rain in August, but never knock it back," he said.
"There are always more dry times than wet, so I'm happy to have it."
Mr Morawitz runs a family operation consisting of cattle, irrigated cropping – mainly cotton – and dryland grains and pulses.
He said the rain would help his chickpea crop, grazing country and the paddocks slated for an upcoming cotton plant.
"It really puts that winter crop in a good place and puts our grass in a great position coming into spring," Mr Morawitz said.
Multiple roads closed
Flooding has closed some roads across Brisbane's north, as well as in the North Burnett and Gladstone regions.
The Burnett Highway is closed at the intersection with the Isis Highway at Ban Ban Springs, Maryborough Biggenden Road is closed at Lakeside and Lowmead Road at Granite Creek is also shut.
Road closures in Brisbane's north include Rasmussen Road in Mount Archer, Moorina Road in Narangba and Mott Street in Strathpine.
The North Burnett Disaster Management Group said it was monitoring the Burnett River levels.
"We've seen a couple of travellers displaced in motels due to the road closures," chair Melinda Jones said.
Bundaberg's Paradise Dam, which is 10 per cent over capacity, has started spilling into the Burnett River.
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Clear skies ahead
The weather system is forecast to clear later on Wednesday.
The BOM is forecasting fine and warm conditions across south-east Queensland for Thursday and into the weekend.
"The latter part of the week will be in complete contrast," senior forecaster Felim Hannify said.
"We will see this moisture flush off the coast during Thursday with a drier end to the week."
Posted, updated