Conditions are intensifying across the south-east Queensland and northern NSW coast, with the Bureau of Meteorology warning Tropical Cyclone Alfred's slow track will bring a "very high risk of significant impacts".

The NSW Premier says the tropical cyclone is acting like "a completely unwanted house guest" - arriving late and will stick around longer.

Four million people are in the firing line of Cyclone Alfred. It's expected to hit between the Sunshine Coast and the Gold Coast - a stretch of Australia known for its beautiful beaches and top surf – as well as Brisbane, Australia's third-biggest city.