The most powerful cyclone for years is showing no signs of weakening as it barrels toward Australia's north Queensland coast, with wind gusts of up to 275 km/h predicted.
Overnight, Australia's Bureau of Meteorology predicted Cyclone Debbie would make landfall as a category 4 tropical cyclone - just one stage below the most dangerous wind speed level.
The state government last night warned 25,000 people living in parts of Mackay to head to higher ground, as dangerous tidal surges of up to 1.7m were forecast.
The Whitsunday Islands were already being battered by wind gusts of up to 190 km/h. Hamilton Island was getting wind roaring through "like a freight train", witness Charlie told the ABC. "The trees are going wild. The place is just shaking continuously."
The cyclone was fast approaching Proserpine, and resident Tina said trees around her house were already falling.
"I can hear trees that are starting to go over, it's frightening. The trees are sort of laying over," she said. "If this is halfway there, goodness, when it's fully here, it's going to be devastating."
The storm was expected to dump heavy rainfall in and around Mackay and Bowen and a flood warning was out for rivers in those areas.
The wind is roaring at Airlie Beach as the cyclone bears down on the coast. It is due to make landfall between Ayr and Midge Point from midday local time.
Senior forecaster Brett Harrison said gusts up to 275 km/h could be generated.
Premier Annastacia Palaszczuk had last night appealed to people in coastal communities in the storm's path to stay indoors and not risk their lives.
"Go to the safest place in your house - the most secure. We are in the stage now where some communities are already in lockdown, so they should not move."
Ms Palaszczuk said the Bureau of Meteorology had advised it could take up to 18 hours for the cyclone's core to pass.
Bruce Gunn from Emergency Management Queensland said the situation was changing rapidly.
"People in the path of the core of the cyclone can expect many, many hours of sheltering," he said.
"Remember that the lull in the winds may be the eye of the cyclone and the destructive winds will return from the opposite direction, so be very careful about going outside."
Mackay residents urged to seek higher ground
More than 25,000 people were warned by text to move from low-lying areas in Mackay by midnight, with fears incoming Cyclone Debbie could cause inundation of up to 1.7m above the high tide level.
The Bureau of Meteorology has warned the storm will be the worst since Cyclone Yasi in 2011, and Ms Palaszczuk said it was "bigger than Marcia" - the category five system that hit Queensland in 2015.
Queensland Fire and Emergency Services (QFES) Commissioner Katarina Carroll said although the latest cyclone tracking map indicated Cyclone Debbie had moved south, residents in Townsville, Ingham, Cardwell and surrounding areas should not be complacent.
"If an official evacuation order has not been issued for your area, the best option is to stay indoors and shelter in place until the cyclone has passed.
"If the building you're sheltering in begins to break up, immediately seek shelter under a strong table or bench or under a heavy mattress.