MORE than 63,000 homes and businesses remain without power in north Queensland, with Mackay residents the latest to be affected by ex-Tropical Cyclone Debbie.

An Energex spokeswoman said 18,000 Mackay residents are waiting for electricity to be restored following damaging winds and flooding rains passing through the coastal town on Tuesday morning.

Some Mackay suburbs had their power cut on Monday evening as a precautionary measure while others lost electricity supply as the low pressure system dumped around 100mm/h as it headed southwest on Tuesday.

"We are getting crews into Mackay as soon as possible, but it will depend on what level of access we get as to how fast we can get people back online," the spokeswoman said.

"We will prioritise with hospital and essential services being connected first in the next 24 hours."

Power is still out in the towns which felt the full force of Cyclone Debbie when it touched down on Monday.

She said crews were still on their way to Bowen and Airlie Beach to assess the damage before they start restoring power to the towns.

"We do know the last two hours they have got people heading into those areas."

Flooding is stranding residents of north Queensland communities already battered by Cyclone Debbie, as forecasters warn the state's southeast to also brace for a drenching.

Floodwaters have cut off the main roads in and out of the cyclone-ravaged towns of Airlie Beach, Bowen and Proserpine.

Motorists tried to leave the tourist town of Airlie Beach on Wednesday but came to an abrupt halt on Shute Harbour Rd, just a few kilometres from their destination.

The Proserpine River spilled over during Cyclone Debbie, all but swallowing road traffic signs and a railway crossing.

Swiftwater rescue crews have come to the aid of three people who were on the top of a car on a flooded road in Childers as the aftermath of ex-tropical cyclone Debbie spreads south.

A Queensland Fire and Rescue Service spokesman confirmed the people had been taken to safety after crews reached them this morning.

The trio had jumped on top of the vehicle to avoid floodwaters on Logging Creek Rd as the Bureau of Meteorology warns of heavy rain leading to possible severe flash flooding for 1300km of Queensland's coast.

Residents in parts of the Bundaberg region are being advised to stock up on supplies as flash flooding causes problems in the area.

Further north, motorists were left stranded in floodwater at Proserpine and the region's main artery, the Bruce Highway, has been cut in multiple places and water is still rising. The Whitsunday Mayor, Andrew Wilcox, has called Bowen "a war zone".