The Bureau of Meteorology issued a fresh warning for heavy to intense rainfall between Ayr and St Lawrence including Mackay, Proserpine and Bowen on Tuesday afternoon.
Senior meteorologist Miriam Bradbury says many catchments have already broken their banks after more than 300mm of rain fell in 24 hours.
"Catchments in central and northern Queensland are saturated and will respond rapidly to further rainfall," she told reporters on Tuesday afternoon.
"Dangerous flash flooding remains possible, particularly around the coast and ranges north of Mackay to Nebo."
The Mackay Regional Council has warned people living in the Sandy Creek, Eton and Kinchant Dam areas that further rainfall could cause more flooding in low-lying parts over the next 12-24 hours.
"Warn friends, family and neighbours in the area. Help others if you can," the council posted on Facebook.
"Make sure you have enough food, water, medicine and pet food for two days. Stay away from rivers and creeks. Stay informed because conditions may change overnight."
Thousands of people in the areas north of Mackay including Bloomsbury, Midge Point, Lethebrook, Laguna Quays, Calen, Pindi Pindi, Yalbaroo, St Helens Beach, Mount Ossa and Seaforth are hemmed in by the deluge.
Acting premier Steven Miles said the priority would be ensuring locals had adequate access to food, water and other supplies, with some areas likely to be isolated for days.
"Our concern at this stage is resupply for those communities who are now isolated," he told reporters.
"Those communities may be isolated for days or even up to a week."
Dozens of travellers have also been stranded in the region with Queensland's main road artery, the Bruce Highway, cleaved by torrents in at least five different places.
Queensland Fire and Emergency Services warned people to stay away from the floodwaters, which in the tropics carry an extra risk as the preferred stalking ground for saltwater crocodiles.
The agency posted a picture of one marine reptile swimming beside a flooded road near Proserpine on Tuesday afternoon.
"Here's just one of the reasons you should stay clear of floodwaters!" QFES wrote on Facebook.
"Can you spot what's lurking in the water near the highway in Proserpine?"
The Bureau of Meteorology has forecast the intense rainfall to start easing to showers from Tuesday night and into Wednesday as the low-pressure system moves offshore.
Showers and thunderstorms across much of northern Australia and inland Queensland have not been a dampener for everyone though, with farmers optimistic about the year ahead.
AgForce chief executive Michael Guerin said the rainfall set up the sector for strong production in the coming months.
"However, producers and industry are keeping a close eye on events and are prioritising human and animal safety in preparation for more widespread flooding," he said in a statement.
"AgForce is also working closely with the State Government on disaster management plans. We encourage producers and communities to stay close to their local disaster coordination centres."
