More than 25,000 Mackay residents have been told by the premier to flee as Cyclone Debbie intensifies just hours from landfall, bringing with it a possibly destructive storm surge.
Premier Annastacia Palaszczuk said on Monday night that Cyclone Debbie had been officially classified a category 4 tropical cyclone and was likely to bring surges of up to 2.5 metres as it hit the coast with the high tide.
"Because of the intensity of the cyclone and the timing at the moment that it's due to cross land, we are very concerned at the moment about the prospective tidal surge in Mackay," Ms Palaszczuk said.
"It's very clear the time for people to move is now.
"I would rather take these precautionary measures now than have people's lives put at risk."
Police Commissioner Ian Stewart said people who could move out of low-lying areas should move immediately.
"Don't wait until tomorrow as you will not be able to move," he said.
"We will do everything we can through emergency services to try and support and assist residents in those low-lying areas... and we will also be getting messages out to help the vulnerable.
"I stress that what we would like people to do is take care of their neighbours as well... it's the Queensland, the Australian way.
"We don't want to see any tragedies occur as a result of this storm... we can't take chances with people's lives."
Residents were encouraged to go to their council websites and check the flood maps and then take action.
Mackay Regional Council has used its website and Facebook page to provide the inundation maps.
"This is not an order to evacuate. However, as advised by the Premier, if you have friends and families in high places, it is recommended that you make arrangements to stay with them," the council's latest update said.
The inundation maps show several parts of Mackay and if they fell into the green zone (up to 0.5 metres above highest astronomical tide), red zone (up to one metre) or orange zones (up to two metres).
Mr Stewart said an evacuation of this magnitude had never been done before.
"This is right across Mackay because of the unique landscape and low-lying areas," he said.
"I know it's a big ask to move this many people but that's the information BoM (the Bureau of Meteorology) is providing us at the moment and because of the time frame and closing window of opportunity for people to move, we just want people to be safe and they can do that if they take action."
With a mass evacuation under way, Mr Stewart advised residents on the road to take it easy, be patient and drive to the conditions.
Cyclone Debbie was upgraded to a category 3 on Sunday, and the bureau had further lifted it to category 4 less than eight hours before it was expected to make landfall between Ayr and Cape Hillsborough - north of Mackay - about 9am on Tuesday.
Ayr, Bowen, Hamilton Island, Airlie Beach and Townsville were likely to be in the firing line.
Cyclone Debbie was expected to bring 120km/h winds and gusts of 240km/h.
