Thousands of Australians have been fleeing their homes as a powerful storm heads towards the state of Queensland.

Cyclone Debbie is expected to be classed as a Category Four storm, just one rung below the highest grade.

Some 30,000 people have been told to evacuate low lying areas most at risk from tidal surges and winds of up to 300km per hour (185mph).

Experts are warning Debbie will be the most powerful storm to hit the state since Cyclone Yasi destroyed homes, crops and holiday resorts in 2011.

Debbie is expected to gather strength before making landfall on Tuesday.